Plating apparatus, plating method and substrate processing apparatus

ABSTRACT

The present invention provides a plating apparatus which uses an insoluble anode and which can perform plating of a substrate stably while preventing oxygen gas, generated due to the use of the insoluble anode, from causing defects in the substrate. The plating apparatus includes: a substrate holder for holding a substrate; a cathode section including a seal ring for contacting a peripheral portion of a surface, to be plated, of the substrate held by the substrate holder to seal the peripheral portion water-tightly, and a cathode for contacting the substrate to supply current to the substrate; a vertically-movable electrode head provided above the cathode section, including an anode chamber housing an anode made of an insoluble material and having a bottom opening closed with a water-permeable porous member; a plating solution injection section for injecting a plating solution between the anode and the surface, to be plated, of the substrate held by the substrate holder; a power source for applying a plating voltage between the cathode and the anode; and a gas discharge line for discharging a gas from the anode chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plating apparatus and a plating method, and more particularly to a plating apparatus and a plating method used for filling a fine circuit pattern formed in a substrate, such as a semiconductor substrate, with metal (interconnect material) such as copper so as to form interconnects.

The present invention also relates to a substrate processing apparatus for use as a substrate holding apparatus in the above plating apparatus, in an etching apparatus for etching away at least part of a thin film or the like formed on or adhering to the surface of a substrate, or in a polishing apparatus for mirror-polishing the surface of a substrate, or the like, and also to a substrate processing method.

2. Description of the Related Art

Recently, there has been employed a circuit forming method comprising forming fine recesses for interconnects, such as interconnect trenches (trenches) or fine holes (via holes) in a circuit form, in a semiconductor substrate, embedding the fine recesses with copper (interconnect material) by copper plating, and removing a copper layer (plated film) at portions other than the fine recesses by means of CMP or the like.

A plating apparatus having the following configuration has been known as this type of plating apparatus used for plating to form fine interconnects having high aspect ratios. A substrate is held in such a state that a surface (surface to be plated) of the substrate faces upward (in a face-up manner). A cathode is brought into contact with a peripheral portion of the substrate so that the surface of the substrate serves as a cathode. An anode is disposed above the substrate. While a space between the substrate and the anode is filled with a plating solution, a plating voltage is applied between the substrate (cathode) and the anode to plate a surface (surface to be plated) of a substrate (for example, see Japanese laid-open patent publication No. 2000-232078).

In a plating apparatus in which a substrate is held and plated in single wafer processing while a surface of the substrate faces upward, a distribution of a plating current can be made more uniform over an entire surface of the substrate to improve uniformity of a plated film over the surface of the substrate. Generally, the substrate is transferred and subjected to various processes in such a state that a surface of the substrate faces upward. Accordingly, it is not necessary to turn the substrate at the time of plating.

It is widely practiced with such a plating apparatus to use a soluble anode made of, for example, copper (phosphor-containing copper) containing 0.03 to 0.05% of phosphor so as to form a collagenous black film comprising a compound of phosphor and chlorine, called black film, on the surface of the anode, thereby suppressing the generation of monovalent copper ions (slime) from the anode.

In the case of using a soluble anode, however, when monovalent copper ions generated from the anode are deposited excessively on the surface of a black film formed on the anode, the black film detaches from the anode and the monovalent copper ions easily become copper. The detached black film itself can cause particles in the plating solution.

It may therefore be considered to use an insoluble anode. When an insoluble anode is used, however, oxygen gas is generated at the anode surface. The oxygen gas, when having reached a substrate, can cause defects in the substrate. Further, the liquid level of plating solution can change due to the pressure of the oxygen gas acting on the surface of the plating solution, making it impossible to carry out stable plating.

On the other hand, as shown in FIG. 1, when forming a copper layer 7 a by copper plating of the surface of a substrate W where narrow trenches 6 a with a width d₁ of, for example, not more than 0.1 μm and broad trenches 6 b with a width d₂ of, for example, about 100 μm are co-present, the growth of the plating film tends to be promoted over the narrow trenches 6 a to raise the copper layer 7 a even when the action of the plating solution or an additive contained in the plating solution is optimized. On the other hand, a high-leveling growth of plating film is not possible in the broad trenches 6 b. As a result, a level difference a+b, i.e. the sum of the height “a” of the raised portions over the narrow trenches 6 a and the depth “b” of the recessed portions over the broad trenches 6 b, is produced in the copper layer 7 a deposited on the substrate W. Accordingly, in order to flatten the surface of the substrate W after embedding of copper in the narrow trenches 6 a and the broad trenches 6 b, it is necessary to make the thickness of the copper layer 7 a sufficiently thick and polish away the copper layer 7 a by CMP in an extra amount corresponding to the level difference a+b.

In CMP processing of a plated film, however, a larger thickness of the plated film requires a larger polishing amount, leading to a prolonged processing time. An increase in the CMP rate to avoid the processing prolongation can cause dishing in broad trenches during the CMP processing.

In order to solve these problems, it is necessary to make a thickness of a plated film as thin as possible, and eliminate raised portions and recesses in the plated film even when narrow trenches and broad trenches are co-present in the surface of the substrate to thereby enhance the flatness. At present, however, when carrying out electroplating using, for example, an electrolytic copper sulfate bath, it is not possible to simultaneously decrease raised portions and recesses solely by the action of the plating solution or an additive.

In-plane uniformity of a thickness of a plated film is a measure for evaluating the plating performance of plating carried out on a semiconductor substrate. It is desirable that the thickness of a plated film formed on a surface of a substrate be uniform over the entire surface, i.e. from the center to the periphery, of a substrate.

According to a common standard., for example, the error range of the diameter of a substrate, such as a 300 mmφ semiconductor wafer, is about ±0.2 mm (300±0.2 mm). It is, therefore, necessary to provide a substrate holding apparatus for holding such a substrate with a mechanism that can absorb about the 0.4 mm error.

FIGS. 2 through 5 schematically show a substrate holding apparatus for use in, for example, an electroplating apparatus. As shown in FIGS. 2 through 5, the substrate holding apparatus includes a substrate holder 12 coupled to the upper end of a vertically-movable spline shaft 10, and a rotating disk 16 coupled to the upper end of a rotatable main shaft 14 surrounding the spline shaft 10. The main shaft 14 is rotatably supported by a housing 18 via a bearing 20, and a ball spline 22 is interposed between the spline shaft 10 and the main shaft 14. The spline shaft 10 thus moves vertically relative to the main shaft 14, and rotates together with the main shaft 14 and the rotating disk 16 by the rotation of the main shaft 14.

A plurality of seats 24, each having a step portion 24 a on the inner side, is provided in the peripheral portion of the substrate holder 12 at a given pitch along the circumferential direction. The step portion 24 a is to make contact with a peripheral portion of the lower surface of a substrate W so as to place thereon and support the substrate W, and is configured to absorb, for example, about 0.4 mm error when holding a 300 mmφ substrate W, as described above. A hooked chuck 26 at its center in the length direction is rotatably supported to the seat 24, and at the lower end is rotatably coupled to the upper end of a pressing rod 30 which is biased downwardly by a helical spring 28.

When the pressing rod 30 moves downwardly by the elastic force of the helical spring 28, the chuck 26 rotates such that it closes inwardly, so that a peripheral portion of the substrate W, placed and supported on the step portion 24 a of the seat 24, is nipped between the step portion 24 a and the front end of the chuck 26. The substrate W is thus held mechanically. When the pressing rod 30 moves upwardly against the elastic force of the helical spring 28, the chuck 26 rotates such that it opens outwardly, so that the nipping of the peripheral portion of the substrate W, placed on the step portion 24 a of the seat 24, between the step portion 24 a and the front end of the chuck 26 is released.

A plurality of support posts 32 is mounted on the peripheral portion of the rotating disk 16 at a given pitch along the circumferential direction. Cathodes 34, which comprise six parts, for example, and a ring-shaped seal ring 36 covering the upper surface of the cathodes 34 are mounted to the top ends of the support posts 32. The seal ring 36 has a downwardly-extending tapered inner peripheral portion which inclines inwardly and downwardly.

As shown in FIG. 4, when the substrate holder 12 rises to a plating position, the cathodes 34 presses on a peripheral portion of the substrate W held by the substrate holder 12 and feeds electricity to the substrate W. At the same time, the inner peripheral end portion of the seal ring 36 comes into pressure contact with a peripheral portion of the upper surface of the substrate W to thereby seal that portion water-tightly, preventing a plating solution, which has been supplied onto the upper surface (surface to be plated) of the substrate W, from leaking out of the peripheral portion of the substrate W and preventing the plating solution from contaminating the cathodes 34.

An extensible bellows 38 is disposed between the substrate holder 12 and the rotating disk 16 to prevent the plating solution from intruding into the mechanism side where the spline shaft 10, etc. are present.

According to the substrate holding apparatus, when the substrate holder 12 is lowered to a position (substrate transfer position) as shown in FIG. 2, the lower end of the pressing rod 30 comes into contact with the upper surface of the rotating disk 16 and the pressing rod 30 is lifted against the elastic force of the helical spring 28, so that the chuck 26 moves outwardly and opens. The apparatus is now in a condition to be able to place the substrate W on the step portion 24 a of the seat 24, or carry the substrate W out of the step portion 24 a.

When the substrate holder 12 is somewhat raised to a position (cleaning position) as shown in FIG. 3, the pressing rod 30 is lowered by the elastic force of the helical spring 28, so that the chuck 26 moves inwardly and closes, whereby the substrate W at the peripheral end is mechanically held by the chuck 26. The apparatus is now in a condition to be able to perform processing of the substrate W, such as pre-plating processing of the substrate W or spin-drying, while rotating the substrate holder 12 together with the rotating disk 16 by rotating the main shaft 14.

When the substrate holder 12 is further raised to a position (plating position) as shown in FIG. 4, the cathodes 34 come to press on a peripheral portion of the substrate W held by the substrate holder 12 and feed electricity to the substrate W. At the same time, the inner peripheral end portion of the seal ring 36 comes into pressure contact with a peripheral portion of the upper surface of the substrate W to water-tightly seal that portion. The apparatus is now in a condition to be able to perform plating by supplying a plating solution onto the surface (upper surface) of the substrate W and applying a voltage between the cathodes 34 and an anode (not shown) disposed above the cathodes 34 such that it faces the substrate W and is immersed in the plating solution.

The seal ring 36 is generally made of a rubber, and may be formed from, for example, a fluorocarbon rubber, a silicone rubber or a variety of elastomers. The seal ring 36 maybe mounted to a metal or resin holder for use.

As described above, according to the conventional substrate holding apparatus, a substrate is fixed by the mechanical chucks on the seats of the substrate holder which are designed in consideration of the maximum tolerance for the diameter of the substrate in order to absorb the dimensional error of the substrate diameter. Accordingly, the absorbed dimensional error of the diameter of a substrate W directly leads to an error in positioning of the substrate W with respect to the substrate holder. For example, when holding a substrate W having a diameter of 299.8 mm (diametrical error: −0.2 mm) with the substrate holding apparatus to process the substrate W, there occurs an error of about 0.4 mm at the maximum in the contact points between the cathodes 34 and the substrate W and in the contact portion between the seal ring 36 and the substrate W in terms of the distances from the edge of the substrate W. When a substrate is held in a substrate holding apparatus with such an inaccurate positioning and brought into contact with cathodes and a seal ring disposed, for example, above the substrate, variation (error) occurs in the contact position between the substrate and the cathodes and in the contact position between the substrate and the seal ring.

Such a variation (error) in the contact position between a substrate and cathodes/seal ring, when the substrate is a next-generation substrate having a thin-film seed layer with a narrow interconnect width or when the substrate is plated with a plating apparatus with a vary small distance between the substrate and the cathodes, makes the flow of electric current at the substrate surface non-uniform, thereby producing a significant difference in the thickness of the plated formed on the surface of the substrate between the central portion and the peripheral portion of the substrate.

On the other hand, with respect to the seal ring 36, as shown in FIG. 5, the deformation of the seal ring 36 generally made of a rubber is large around the contact surface between the seal ring 36 and a substrate Wand, depending upon how it is pressed against the substrate W, a non-uniform deformation occurs in the seal ring 36. The non-uniform deformation of the seal ring 36 can lead to a twist in the sealing surface, causing a leak of plating solution. Further, the distance between the peripheral end of the substrate W and the sealing boundary can be varied, which would adversely affect in-plane uniformity of the thickness of the plated film after plating.

Though a substrate holding apparatus for a plating apparatus has been described hereinabove, the same problems are involved in substrate holding apparatuses for other electrolytic processing apparatuses, such as an electrolytic etching apparatus, or for a polishing apparatus, etc.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above situation in the related art. It is therefore a first object of the present invention to provide a plating apparatus which uses an insoluble anode and which can perform plating of a substrate stably while preventing oxygen gas, generated due to the use of the insoluble anode, from causing defects in the substrate.

It is a second object of the present invention to provide a plating apparatus and a plating method which can deposit a metal plated film, such as a copper plated film, selectively in interconnect trenches and fine holes formed in the surface of a substrate.

It is a third object of the present invention to provide a substrate processing apparatus and method which can hold a substrate in a substrate holder with accurate positioning of the substrate with respect to the substrate holder, without being influence by a diametrical error of the substrate, and can perform various processing processes such as electroplating.

In order to achieve the above object, the present invention provides a plating apparatus comprising: a substrate holder for holding a substrate; a cathode section including a seal ring for contacting a peripheral portion of a surface, to be plated, of the substrate held by the substrate holder to seal the peripheral portion water-tightly, and a cathode for contacting the substrate to supply current to the substrate; a vertically-movable electrode head provided above the cathode section, including an anode chamber housing an anode made of an insoluble material and having a bottom opening closed with a water-permeable porous member; a plating solution injection section for injecting a plating solution between the anode and the surface, to be plated, of the substrate held by the substrate holder; a power source for applying a plating voltage between the cathode and the anode; and a gas discharge line for discharging gas from the anode chamber.

The use of an anode made of an insoluble material can avoid the need for a change of anode and, in addition, obviate the generation of particles due to the peeling of a black film which would occur when using a soluble anode. Further, oxygen gas generated at the surface of the insoluble anode during plating can be introduced into the anode chamber, and the oxygen gas in the anode chamber can then be discharged so that the oxygen gas will not reach the substrate.

Preferably, the plating apparatus further comprises a control section for controlling an amount of the gas discharged through the gas discharge line.

By controlling the amount of the gas discharged through the gas discharge line with the control section so as to keep the pressure in the anode chamber constant, the liquid surface level of the plating solution in the anode chamber can be prevented from changing, enabling stable plating.

In a preferred embodiment of the present invention, the plating apparatus further comprises a pressure sensor for detecting the pressure in the anode chamber, and the control section controls the amount of the gas discharged through the gas discharge line based on an output of the pressure sensor.

By detecting the pressure in the anode chamber with the pressure sensor and performing a feedback control by, for example, operating a vacuum pump in proportion to the detected pressure, the pressure in the anode chamber can be kept constant.

In a preferred embodiment of the present invention, the plating apparatus further comprises an integrator for integrating an electric current flowing between the cathode and the anode, and the control section controls the amount of the gas discharged through the gas discharge line based on an output of the integrator.

The amount of oxygen gas generated at the anode surface during plating is proportional to the electric current flowing between the substrate (cathode) connected to the cathode and the anode. Accordingly, by integrating the electric current and performing a feedforward control by, for example, operating a vacuum pump in proportion to the integrated current value, the pressure in the anode chamber can be kept constant.

The present invention also provides a plating method comprising: providing in a plating cell an anode and a plating solution impregnated material disposed above the anode, and filing a plating solution into the plating cell until the plating solution reaches to above the plating solution impregnated material; bringing a downwardly-facing surface, to be plated, of a substrate into contact with the plating solution above the plating solution impregnated material; and applying a voltage between the anode and the surface to be plated of the substrate, thereby carrying out plating of the surface, to be plated.

By interposing the plating solution impregnated material, which serves as a high-resistance structure, between the substrate and the anode, it becomes possible to effect uniform plating over the entire surface, to be plated, of the substrate. Further, by holding the substrate with its surface, to be plated, facing downwardly (face down), and providing the plating solution impregnated material on the anode side, the diametrical size of the plating solution impregnated material can be easily made large relative to the diametrical size of the substrate, ensuring uniform plating. Further, the plating solution impregnated material can prevent a so-called black film, which can be formed on the anode during plating, from moving to the substrate side.

In a preferred embodiment of the present invention, a contact member is provided on the upper surface of the plating solution impregnated material, and plating is carried out while keeping the surface, to be plated, of the substrate in contact with the upper surface of the contact member.

By thus carrying out plating while keeping the surface, to be plated, of the substrate in contact with the upper surface of the contact member, the plating solution can be supplied preferentially into interconnect trenches and fine holes formed in the surface, to be plated, of the substrate, thus making it possible to preferentially (selectively) deposit a metal plated film, such as a copper plated film, on the surfaces of the interconnect trenches and fine holes. In particular, when plating is carried out by allowing a contact member, having such fine through-holes as to permit passage of the plating solution, in contact with an electrical conductor layer on the surface, to be plated, of the substrate, the plating solution flows into interconnect trenches and fine holes, but it little flows between the flat portion of the substrate and the contact member, resulting in preferential deposition of a metal on the surfaces of the interconnect trenches and the fine holes.

Preferably, the operation of applying a voltage between the surface, to be plated, of the substrate and the anode while keeping the surface, to be plated, in contact with the upper surface of the contact member and the operation of detaching the surface, to be plated, of the substrate from the upper surface of the contact member are repeated.

When the surface, to be plated, of the substrate is detached from the upper surface of the contact member, a fresh plating solution can flow into interconnect trenches and fine holes on the substrate more easily, thus facilitating selective metal plating onto the surfaces of the interconnect trenches and the fine holes.

Preferably, the substrate is allowed to rotate or make a scroll movement while the surface, to be plated, of the substrate is kept in contact with the plating solution.

By allowing the substrate to rotate or make a scroll movement, plating can be effected move uniformly over the entire surface, to be plated, of the substrate. The rotation or scroll movement of the substrate may be carried out either when the substrate is in contact with the contact member or when the substrate is apart from the contact member.

In a preferred embodiment of the present invention, the plating solution is supplied into the plating cell from below the plating solution impregnated material, and the plating solution is passed through the plating solution impregnated material and supplied to above the plating solution impregnated material.

Even when the plating solution is supplied from below to above the plating solution impregnated material, because of the plating solution impregnated material (and the upper contact member) that functions as a filter, particles, such as those coming from a black film, produced on the anode side can be prevented from moving to above the plating solution impregnated material (and the upper contact member).

It is also possible to supply the plating solution from above the plating solution impregnated material onto the upper surface of the plating solution impregnated material.

This makes it possible to easily control the composition (amounts of ions, amounts of additives and composition of additives) of the plating solution on the anode side and the composition of the plating solution above the plating solution impregnated material and for use in plating respectively at the optima (the two compositions may be identical).

The present invention also provides another plating apparatus comprising: an anode disposed in a plating cell; a plating solution impregnated material disposed above the anode; a plating solution supply section for supplying and filling a plating solution into the plating cell until the plating solution reaches to above the plating solution impregnated material; and a substrate holder for holding a substrate with its surface, to be plated, facing downwardly; wherein the surface, to be plated, of the substrate held by the substrate holder is brought into contact with the plating solution above the plating solution impregnated material to carry out plating of the surface, to be plated.

In a preferred embodiment of the present invention, the plating apparatus further comprises a contact member having a flat upper surface as a contact surface, provided above the plating solution impregnated material, and a holder drive mechanism for repeating the operation of bringing the surface, to be plated, of the substrate held by the substrate holder into contact with the contact surface of the contact member and the operation of detaching the surface, to be plated, from the contact surface of the contact member.

Preferably, the holder drive mechanism includes a mechanism for vertically moving the substrate holder, and a mechanism for allowing the substrate holder to rotate or make a scroll movement.

The plating solution supply section may include a plating solution supply pipe for supplying the plating solution into the plating cell from below the anode, and a plating solution supply pipe for supplying the plating solution to above the plating solution impregnated material.

Preferably, a filter is provided between the anode and the plating solution impregnated material.

The present invention also provides a substrate processing apparatus comprising: a vertically-movable substrate holder for supporting a substrate in a horizontal position and detachably holding the substrate; and a positioning guide disposed such that it surrounds the circumference of the substrate holder; wherein the positioning guide has a tapered surface which, when the substrate supported horizontally by the substrate holder is lowered or raised, contacts the peripheral end surface of the substrate to position the substrate with respect to the substrate holder.

According to this substrate processing apparatus, positioning of a substrate with respect to the substrate holder is performed by bringing the peripheral end surface as a reference into contact with the tapered surface of the positioning guide. In this positioning, the center position of the substrate does not change regardless of the diameter of the substrate, i.e., regardless of any dimensional error in the diameter. Thus, positioning of the substrate with respect to the substrate holder can be performed with accuracy without being influenced by the diametrical size of the substrate. In particular, when there is a dimensional error in the diametrical size of a substrate, though the height position of the substrate with respect to the positioning guide changes upon contact of the substrate in a horizontal position with the tapered surface of the positioning guide, the center position of the substrate with respect to the guide does not change. Accordingly, when the substrate is attracted and held by the substrate holder, for example, by means of a vacuum chuck, the center of the substrate can coincide with the center of the substrate holder.

In a preferred embodiment of the present invention, the positioning guide is formed in a cylindrical shape, and the tapered surface contacts the peripheral end surface of the substrate over substantially the entire circumference of the peripheral end surface to position the substrate with respect to the substrate holder.

According to this embodiment, substantially the entire circumference of the peripheral end surface of a substrate can be utilized as a reference. This enables a more accurate positioning of the substrate with respect to the substrate holder. The positioning guide in a cylindrical shape may have a cut-off portion e.g. for handling.

Preferably, an electrode for contacting a peripheral portion of the substrate held by the substrate holder to supply current to the substrate and a seal ring for pressure-contacting a peripheral portion of the substrate to seal the peripheral portion are provided above the substrate holder.

The substrate pressing apparatus, when employed in a plating apparatus, enables accurate positioning of a substrate held by the substrate with respect to the cathode and the seal ring. Thus, the distances of the contact positions of the substrate with the cathode and the seal ring from the peripheral end of the substrate can be made uniform, whereby the in-plane uniformity of the thickness of plated film can be enhanced for substrates of various diametrical sizes.

The seal ring is preferably composed of a composite material comprising a metal covered with a rubber.

The seal ring composed of such a material has an enhanced rigidity and improved shape stability. When a substrate is sealed with such a seal ring, the deformation of the seal ring can be small enough to securely prevent a leak of plating solution, etc. Further, because of the high dimensional accuracy of the seal ring, the distance of the sealing boundary from the peripheral end surface of the substrate can be made substantially equal constantly.

The substrate holder is preferably designed to hold the substrate by vacuum attraction.

The use of such a substrate holder can avoid the need to provide an outwardly-projecting holding member, such as a mechanical chuck, and can securely hold a substrate supported by the positioning guide.

Preferably, a temperature control section for controlling the temperature of the substrate holder is provided within the substrate holder.

By controlling not only the temperature of a chemical liquid, such as a plating solution, but also the temperature of the substrate holder and a substrate held by the holder at a constant temperature, the effect of a chemical liquid, which is supplied to the substrate upon processing of the substrate, can be maximized. The temperature control section may be comprised of, for example, an electric heater, a Peltier device or a thermocouple.

The temperature control section, for example, comprises a fluid flow passage for allowing a temperature-controlled heat medium to flow therein.

A heating medium or a cooling medium is used as a heat medium.

The present invention also provides a substrate processing method comprising: lowering or raising a substrate supported horizontally by a substrate holder and bringing a peripheral end surface of the substrate into contact with a tapered surface of a positioning guide, disposed such that it surrounds the substrate holder, to position the substrate with respect to the substrate holder; and holding the substrate by the substrate holder.

Preferably, the tapered surface of the positioning guide is brought into contact with the peripheral end surface of the substrate over substantially the entire circumference of the peripheral end surface to position the substrate with respect to the substrate holder.

The substrate held by the substrate holder may be raised so as to bring an electrode into contact with a peripheral portion of the substrate to supply current to the substrate, and bring a seal ring into pressure contact with a peripheral portion of the substrate to seal the peripheral portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a problem in the prior art involved in the formation of embedded interconnects by copper plating of a substrate;

FIG. 2 is a schematic view of a conventional substrate holding apparatus for use in an electroplating apparatus, showing the state of the apparatus before holding of a substrate by a substrate holder;

FIG. 3 is a schematic view of the conventional substrate holding apparatus for use in the electroplating apparatus, showing the state of the apparatus upon holding of the substrate by the substrate holder;

FIG. 4 is a schematic view of the conventional substrate holding apparatus for use in the electroplating apparatus, showing the state of the apparatus when the substrate holder holding the substrate is raised to a plating position;

FIG. 5 is an enlarged diagram illustrating the relationship between the seal ring of the conventional substrate holding apparatus for use in the electroplating apparatus and a substrate;

FIG. 6A through 6D are views showing an example for forming interconnects in the semiconductor device in a sequence of steps;

FIG. 7 is a plan view of a substrate processing apparatus provided with a plating apparatus according to an embodiment of the present invention;

FIG. 8 is a schematic view of the main portion of the plating apparatus shown in FIG. 7;

FIG. 9 is a schematic view of a plating apparatus according to another embodiment of the present invention;

FIG. 10 is a systematic diagram showing an example of a plating solution management system;

FIG. 11 is a front cross-sectional view showing an example of a cleaning and drying apparatus shown in FIG. 7;

FIG. 12 is a plan view of FIG. 11;

FIG. 13 is a schematic view showing an example of a bevel etching and backside cleaning apparatus shown in FIG. 7;

FIG. 14 is a plan cross-sectional view showing an example of a heating treatment apparatus shown in FIG. 7;

FIG. 15 is a plan cross-sectional view of FIG. 14;

FIG. 16 is a front view of a pretreatment apparatus shown in FIG. 7 at the time of substrate transfer;

FIG. 17 is a front view of the pretreatment apparatus shown in FIG. 7 at the time of chemical treatment;

FIG. 18 is a front view of the pretreatment apparatus shown in FIG. 7 at the time of rinsing;

FIG. 19 is a cross-sectional view showing a processing head at the time of substrate transfer;

FIG. 20 is an enlarged view of A portion of FIG. 19;

FIG. 21 is a view corresponding to FIG. 15 at the time of substrate fixing;

FIG. 22 is a systematic diagram of the pretreatment apparatus shown in FIG. 7;

FIG. 23 is a cross-sectional view showing a substrate head at the time of substrate transfer in an electroless plating apparatus shown in FIG. 7;

FIG. 24 is an enlarged view of B portion of FIG. 23;

FIG. 25 is a view corresponding to FIG. 23 showing the substrate head at the time of substrate fixing;

FIG. 26 is a view corresponding to FIG. 23 showing the substrate head at the time of plating process;

FIG. 27 is a front view with partially cross-section showing a plating tank when a plating tank cover of the pretreatment apparatus shown in FIG. 7 is closed;

FIG. 28 is a cross-sectional view of a cleaning tank in the pretreatment apparatus shown in FIG. 7;

FIG. 29 is a systematic diagram of the cleaning tank in the pretreatment apparatus shown in FIG. 7;

FIG. 30 is a schematic view showing an example of a polishing apparatus shown in FIG. 7;

FIG. 31 is a schematic front view of neighborhood of a reversing machine in a film thickness measuring instrument shown in FIG. 7;

FIG. 32 is a plan view of a reversing arm section of FIG. 31;

FIG. 33 is a flow chart in a substrate processing apparatus shown in FIG. 7;

FIG. 34 is a schematic view of a plating apparatus according to yet another embodiment of the present invention;

FIG. 35 is a diagram schematically showing the contact surface and its vicinity when the contact member of the plating apparatus shown in FIG. 34 is in contact with the surface, to be plated, of a substrate;

FIG. 36 is a diagram schematically showing a current change (A) in fine recesses of a substrate and a current change (B) in the other surface portion of the substrate as observed in plating carried out at a constant voltage according to a plating method of the present invention;

FIG. 37 is an overall plan view of a plating processing facility incorporating the plating apparatus shown in FIG. 34;

FIG. 38 is a schematic view of an electroplating apparatus provided with a substrate processing apparatus, as a substrate holding apparatus, according to an embodiment of the present invention, showing the state of the plating apparatus during plating;

FIG. 39 is a schematic view of the main portion of the substrate holding apparatus (substrate processing apparatus) shown in FIG. 38, showing the state of the apparatus before holding of a substrate by a substrate holder;

FIG. 40 is a schematic view of the main portion of the substrate holding apparatus (substrate processing apparatus) shown in FIG. 38, showing the state of the apparatus after holding of the substrate by the substrate holder; and

FIGS. 41A and 41B are enlarged diagrams illustrating the relationship between the seal ring of the substrate holding apparatus shown in FIG. 38 and a substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below with reference to the drawings. The following embodiments show examples in which copper as an interconnect material is embedded in fine recesses for interconnects formed in a surface of a substrate such as a semiconductor wafer so as to form interconnects composed of a copper layer. However, it is of course possible to use other kinds of interconnect materials instead of copper.

An example of forming copper interconnects in a semiconductor device will be described with reference to FIGS. 6A through 6D. As shown in FIG. 6A, an insulating film 2, such as an oxide film of SiO₂ or a film of low-k material, is deposited on a conductive layer la formed on a semiconductor base 1 having formed semiconductor devices. Fine holes (via holes) 3 and interconnect trenches (trenches) 4 are formed in the insulating film 2 by performing a lithography/etching technique so as to provide fine recesses for interconnects. Thereafter, a barrier layer 5 of TaN or the like is formed on the insulating film 2, and a seed layer 6 as a feeding layer for electroplating is formed on the barrier layer 5 by sputtering or the like.

Then, as shown in FIG. 6B, copper plating is performed on a surface of a substrate W to fill the fine holes 3 and the interconnect trenches 4 with copper and, at the same time, deposit a copper layer 7 on the insulating film 2. Thereafter, the barrier layer 5, the seed layer 6 and the copper layer 7 on the insulating film 2 are removed by chemical mechanical polishing (CMP) or the like so as to make a surface of copper layer filled in the fine holes 3 and the interconnect trenches 4, and a surface of the insulating film 2 lie substantially on the same plane. Interconnects (copper interconnects) 8 composed of the seed layer 6 and the copper layer 7 are thus formed in the insulating film 2 as shown in FIG. 6C.

Then, as shown in FIG. 6D, electroless plating is performed on a surface of the substrate W to selectively form a protective film 9 of a Co alloy, an Ni alloy, or the like on surfaces of the interconnects 8, thereby covering and protecting the surfaces of the interconnects 8 with the protective film 9.

FIG. 7 is a plan view of a substrate processing apparatus provided with a plating apparatus according to an embodiment of the present invention. As shown in FIG. 7, the substrate processing apparatus comprises a rectangular apparatus frame 812 to which transfer boxes 810 such as SMIF boxes, which accommodate a number of substrates such as semiconductor wafers, are removably attached. Inside of the apparatus frame 812, there are disposed a loading/unloading station 814, and a movable transfer robot 816 for transferring a substrate to and from the loading/unloading station 814. A pair of plating apparatuses 818 is disposed on both sides of the transfer robot 816. A cleaning and drying apparatus 820, a bevel etching and backside cleaning apparatus 822, and a film thickness measuring instrument 824 are disposed in alignment with each other on one side of the transfer robot 816. On the other side of the transfer robot 816, a heat treatment (annealing) apparatus 826, a pretreatment apparatus 828, an electroless plating apparatus 830, and a polishing apparatus 832 are disposed in alignment with each other.

The apparatus frame 812 is shielded so as not to allow a light to transmit therethrough, thereby enabling subsequent processes to be performed under a light-shielded condition in the apparatus frame 812. Specifically, the subsequent processes can be performed without irradiating the interconnects with a light such as an illuminating light. By thus preventing the interconnects from being irradiated with a light, it is possible to prevent the interconnects of copper from being corroded due to a potential difference of light that is caused by application of light to the interconnects composed of copper, for example.

FIG. 8 schematically shows the plating apparatus 818. As shown in FIG. 8, the plating apparatus 818 comprises a swing arm 500 which is horizontally swingable. An electrode head 502 is rotatably supported by a tip end portion of the swing arm 500. A substrate holder 504 for holding a substrate W in such a state that a surface, to be plated, of the substrate W faces upwardly is vertically movably disposed below the electrode head 502. A cathode section 506 is disposed above the substrate holder 504 so as to surround a peripheral portion of the substrate holder 504. In this embodiment, the electrode head 502 whose diameter is slightly smaller than that of the substrate holder 504 is used so that plating can be performed over the substantially entire surface, to be plated, of the substrate W without changing a relative position between the electrode head 502 and the substrate holder 504.

An annular vacuum attraction groove 504 b communicating with a vacuum passage 504 a provided in the substrate holder 504 is formed in a peripheral portion of an upper surface of the substrate holder 504. Seal rings 508 and 510 are provided on inward and outward sides of the vacuum attraction groove 504 b, respectively. With the above structure, the substrate W is placed on the upper surface of the substrate holder 504, and the vacuum attraction groove 504 b is evacuated through the vacuum passage 504 a to attract the peripheral portion of the substrate W, thereby holding the substrate W.

An elevating/lowering motor (not shown) comprising a servomotor and a ball screw (not shown) are used to move the swing arm 500 vertically, and a swinging motor (not shown) is used to rotate (swing) the swing arm 500. Alternatively, a pneumatic actuator may be used instead of the motor.

In this embodiment, the cathode section 506 has the cathodes 512 comprising six cathodes, and the annular seal member 514 disposed above the cathodes 512 so as to cover upper surfaces of the cathodes 512. The seal member 514 has an inner circumferential portion which is inclined inwardly and downwardly so that a thickness of the seal member 514 is gradually reduced. The seal member 514 has an inner circumferential edge portion extending downwardly. With this structure, when the substrate holder 504 is moved upwardly, the peripheral portion of the substrate W held by the substrate holder 504 is pressed against the cathodes 512, thus flowing current to the substrate W. At the same time, the inner circumferential edge portion of the seal member 514 is held in close contact with the upper surface of the peripheral portion of the substrate W to seal a contact portion in a watertight manner. Accordingly, a plating solution that has been supplied onto the upper surface (surface to be plated) of the substrate W is prevented from leaking from the end portion of the substrate W, and the cathodes 512 are thus prevented from being contaminated by the plating solution.

In this embodiment, the cathode section 506 is not movable vertically, but is rotatable together with the substrate holder 504. However, the cathode section 506 maybe designed to be movable vertically so that the seal member 514 is brought into close contact with the surface, to be plated, of the substrate W when the cathode section 506 is moved downwardly.

The electrode head 502 comprises a rotatable housing 520 and a vertically movable housing 522 which have a bottomed cylindrical shape with a downwardly open end and are disposed concentrically. The rotatable housing 520 is fixed to a lower surface of a rotating member 524 attached to a free end of the swing arm 500 so that the rotatable housing 520 is rotated together with the rotating member 524. An upper portion of the vertically movable housing 522, on the other hand, is positioned inside the rotatable housing 520, and the vertically movable housing 522 is rotated together with the rotatable housing 520 and is moved relative to the rotatable housing 520 in a vertical direction. The vertically movable housing 522 defines an anode chamber 530 by closing the lower open end of the vertically movable housing 522 with a porous member 528 so that a circular anode 526 is disposed in the anode chamber 530 and is dipped in a plating solution which is introduced to the anode chamber 530.

In this embodiment, the porous member 528 has a multi-layered structure comprising three-layer laminated porous materials. Specifically, the porous member 528 comprises a plating solution impregnated material 532 serving to hold a plating solution mainly, and a porous pad 534 attached to a lower surface of the plating solution impregnated material 532. This porous pad 534 comprises a lower pad 534 a adapted to be brought into direct contact with the substrate W, and an upper pad 534 b disposed between the lower pad 534 a and the plating solution impregnated material 532. The plating solution impregnated material 532 and the upper pad 534 b are positioned in the vertically movable housing 522, and the lower open end of the vertically movable housing 522 is closed by the lower pad 534 a.

As described above, since the porous member 528 has a multi-layered structure, it is possible to use the porous pad 534 (the lower pad 534 a) which contacts the substrate W, for example, and has flatness enough to flatten irregularities on the surface, to be plated, of the substrate W.

The lower pad 534 a is required to have the contact surface adapted to contact the surface (surface to be plated) of the substrate W and having a certain degree of flatness, and to have fine through-holes therein for allowing the plating solution to pass therethrough. It is also necessary that at least the contact surface of the lower pad 534 a is made of an insulator or a material having high insulating properties. The surface of the lower pad 534 a is required to have a maximum roughness (RMS) of about several tens μm or less.

It is desirable that the fine through-holes of the lower pad 534 a have a circular cross section in order to maintain flatness of the contact surface. An optimum diameter of each of the fine through-holes and the optimum number of the fine through-holes per unit area vary depending on the kind of a plated film and an interconnect pattern. However, it is desirable that both the diameter and the number are as small as possible in view of improving selectivity of a plated film which is growing in a recess. Specifically, the diameter of each of the fine through-holes may be not more than 30 μm, preferably in the range of 5 to 20 μm. The number of the fine through-holes having such diameter per unit area may be represented by a porosity of not more than 50%.

Further, it is desirable that the lower pad 534 a has a certain degree of hardness. For example, the lower pad 534 a may have a tensile strength ranging from 5 to 100 kg/cm² and a bend elastic constant ranging from 200 to 10000 kg/cm².

Furthermore, it is desirable that the lower pad 534 a is made of hydrophilic material. For example, the following materials may be used after being subjected to hydrophilization or being introduced with a hydrophilic group by polymerization. Examples of such materials include porous polyethylene (PE), porous polypropylene (PP), porous polyamide, porous polycarbonate, and porous polyimide. The porous PE, the porous PP, the porous polyamide, and the like are produced by using fine powder of ultrahigh-molecular polyethylene, polypropylene, and polyamide, or the like as a material, squeezing the fine powder, and sintering and forming the squeezed fine powder. These materials are commercially available. For example, “Furudasu S (tradename) “manufactured by Mitsubishi Plastics, Inc, “Sunfine UF (trade name)”, “Sunfine AQ (trade name)”, both of which are manufactured by Asahi Kasei Corporation, and “Spacy (trade name)” manufactured by Spacy Chemical Corporation are available on the market. The porous polycarbonate may be produced by passing a high-energy heavy metal such as copper, which has been accelerated by an accelerator, through a polycarbonate film to form straight tracks, and then selectively etching the tracks.

The lower pad 534 a may be produced by a flattening process in which the surface, to be brought into contact with the surface of the substrate W, of the lower pad 534 a is compacted or machined to a flat finish for thereby enabling a high-preferential deposition in the fine recesses.

On the other hand, the plating solution impregnated material 532 is composed of porous ceramics such as alumina, SiC, mullite, zirconia, titania or cordierite, or a hard porous member such as a sintered compact of polypropylene or polyethylene, or a composite material comprising these materials. The plating solution impregnated material 532 maybe composed of a woven fabric or a non-woven fabric. In case of the alumina-based ceramics, for example, the ceramics with a pore diameter of 30 to 200 μm is used. In case of the SiC, SiC with a pore diameter of not more than 30 μm, a porosity of 20 to 95%, and a thickness of about 1 to 20 mm, preferably 5 to 20 mm, more preferably 8 to 15 mm, is used. The plating solution impregnated material 532, in this embodiment, is composed of porous ceramics of alumina having a porosity of 30%, and an average pore diameterof 100 μm. Theporous ceramic plate per se is an insulator, but is constructed so as to have a smaller conductivity than the plating solution by causing the plating solution to enter its inner part complicatedly and follow a considerably long path in the thickness direction.

In this manner, the plating solution impregnated material 532 is disposed in the anode chamber 530, and generates high resistance. Hence, the influence of the resistance of the copper layer 7 (see FIG. 6B) becomes a negligible degree. Consequently, the difference in current density over the surface of the substrate due to electrical resistance on the surface of the substrate W becomes small, and the uniformity of the plated film over the surface of the substrate improves.

The electrode head 502 has a pressing mechanism comprising an air bag 540 in this embodiment for pressing the lower pad 534 a against the surface (surface to be plated) of the substrate W held by the substrate holder 504 under a desired pressure. Specifically, in this embodiment, a ring-shaped air bag (pressing mechanism) 540 is provided between the lower surface of the top wall of the rotatable housing 520 and the upper surface of the top wall of the vertically movable housing 522, and this air bag 540 is connected to a pressurized fluid source (not shown) through a fluid introduction pipe 542.

Thus, the swing arm 500 is fixed at a predetermined position (process position) so as not to move vertically, and then the inner part of the air bag 540 is pressurized under a pressure of P, whereby the lower pad 534 a is uniformly pressed against the surface (surface to be plated) of the substrate W held by the substrate holder 504 under a desired pressure. Thereafter, the pressure P is restored to an atmospheric pressure, whereby pressing of the lower pad 534 a against the substrate W is released.

A plating solution introduction pipe 544 is attached to the vertically movable housing 522 to introduce the plating solution into the vertically movable housing 522, and a pressurized fluid introduction pipe (not shown) is attached to the vertically movable housing 522 to introduce a pressurized fluid into the vertically movable housing 522. A number of pores 526 a are formed within the anode 526. Thus, a plating solution Q is introduced from the plating solution introduction pipe 544 into the anode chamber 530, and the inner part of the anode chamber 530 is pressurized, whereby the plating solution Q reaches the upper surface of the plating solution impregnated material 532 through the pores 526 a of the anode 526, and reaches the upper surface of the substrate W held by the substrate holder 504 through the inner part of the plating solution impregnated material 532 and inner part of the porous pad 534 (the upper pad 534 b and the lower pad 534 a).

The anode 526 is composed of an insoluble metal, such as platinum, titanium, etc., or of an insoluble electrode comprising a metal base plated or coated with a metal, such as platinum, for example, an electrode comprising a titanium base and an iridium coating. The use of the anode 526 composed of an insoluble material (insoluble electrode) can avoid the need for a change of the anode 526 and, in addition, obviate the generation of particles due to the peeling of a black film which would occur when using a soluble anode. However, oxygen gas is generated at the surface of the anode 526 during plating. The oxygen gas, when it reaches the surface of the substrate W, can cause defects in the substrate. In view of this, the plating apparatus of this embodiment has the following construction.

A gas discharge port 564 is mounted to the top wall of the vertically movable housing 522 that defines the anode chamber 530, and a gas discharge line 570, provided with a shut-off valve 566 and a vacuum pump 568, is connected to the gas discharge port 564. In carrying out plating, the shut-off valve 566 is opened and the vacuum pump 568 is driven to vacuum-evacuate the anode chamber 530, so that oxygen gas generated at the surface of the anode 526 passes through the pores 526 a of the anode 526 and reaches the top of the anode chamber 530, and is discharged through the gas discharge line 570. In this manner, the oxygen gas is prevented from reaching the surface of the substrate W.

The plating apparatus of this embodiment is provided with a pressure sensor 572 for detecting the pressure in the anode chamber 530. A signal from the pressure sensor 572 is inputted into a control section 574. Based on an output signal from the control section 574, the operation of the vacuum pump 568 is feedback-controlled so that the pressure in the anode chamber 530 is kept constant. By thus controlling the amount of gas discharged through the gas discharge line 570 so as to keep the pressure in the anode chamber 530 constant, the liquid surface level of the plating solution in the anode chamber 530 can be prevented from changing, enabling stable plating.

As shown in FIG. 9, instead of the pressure sensor 572, it is also possible to provide an integrator 580 for integrating an electric current that flows between the anode 526 and the substrate W connected to the cathodes 512 when a voltage is applied from a power source 550 to between the cathodes 512 and the anode 526. An output from the integrator 580 is inputted into the control section 574, and the operation of the vacuum pump 568 is feed forward-controlled so that the pressure in the anode chamber 530 is kept constant.

The amount of oxygen gas generated at the surface of the anode 526 during plating is proportional to the electric current flowing between the substrate (cathode) W connected to the cathodes 512 and the anode 526. Accordingly, by integrating the electric current and performing a feedforward control by operating the vacuum pump 568 in proportion to the integrated current value, the pressure in the anode chamber 530 can be kept constant.

The cathodes 512 and the anode 526 are electrically connected to the cathode and the anode of the plating power source 550, respectively.

The operation of the plating apparatus in carrying out plating will now be described. First, a substrate W is held, by vacuum attraction, on the upper surface of the substrate holder 504, and the substrate holder 504 is raised to bring a peripheral portion of the substrate W into contact with the cathodes 512 so as to place the substrate in an electricity-passable condition. The substrate holder 504 is further raised to bring a peripheral portion of the upper surface of the substrate W into pressure contact with the seal ring 514 to water-tightly seal the peripheral portion of the substrate W.

The electrode head 502, on the other hand, is moved from a position (idling position) at which idling is performed for replacement and removal of bubbles of the plating solution to a predetermined position (processing position) while the plating solution is kept held in the electrode head 502. In particular, the swing arm 500 is raised and then swung to move the electrode head 502 to a position right above the substrate holder 504. Thereafter, the electrode head 502 is lowered and is stopped when it has reached the predetermined position (processing position). The anode chamber 530 is internally pressurized so as to emit the plating solution, held in the electrode head 502, from the lower surface of the porous pad 534. Thereafter, pressurized air is introduced into the air bag 340 to press on the lower pad 534 a downwardly.

Thereafter, the electrode head 502 and the substrate holder 504 are respectively rotated while the entire surface of the porous member 528 (lower pad 534 a) is kept in contact with the surface to be plated of the substrate W at a uniform pressure.

Next, the cathodes 512 are connected to the cathode of the plating power source 550 and the anode 526 is connected to the anode of the plating power source 550, thereby effecting plating of the surface to be plated of the substrate W. During the plating, the shut-off valve 566 of the gas discharge line 570 is opened and the vacuum pump 568 is operated while it is controlled so that the pressure in the anode chamber 530 is kept constant, thereby discharging gas from the anode chamber 530. This prevents oxygen gas generated at the surface of the anode 526 during plating from reaching the substrate W and also prevents the liquid surface level of the plating solution in the anode chamber 530 from changing.

After carrying out plating for a predetermined time, the cathodes 512 and the anode 526 are disconnected to the plating power source 550, and the shut-off valve 566 is closed to return the internal pressure of the anode chamber 530 to atmospheric pressure. The internal pressure of the air bag 540 is also returned to atmospheric pressure to thereby release the pressure of the lower pad 534 a on the substrate W. Thereafter, the electrode head 502 is raised.

The above operation is repeated a number of times, according to necessity, so as to form a copper layer 7 (see FIG. 6B), having a sufficient thickness to fill in fine interconnect recesses, on the surface (surface to be plated) of the substrate W. Thereafter, the electrode head 502 is swung to return it to the original position (idling position).

FIG. 10 shows a plating solution management and supply system for supplying a plating solution whose composition, temperature, and the like are controlled to the plating apparatus 818. As shown in FIG. 10, a plating solution tray 600 for allowing the electrode head 502 of the plating apparatus 818 to be immersed for idling is provided, and the plating solution tray 600 is connected to a reservoir 604 through a plating solution discharge pipe 602. The plating solution discharged through the plating solution discharge pipe 602 flows into the reservoir 604.

The plating solution, which has flowed into the reservoir 604, is introduced into the plating solution regulating tank 608 by operating a pump 606. This plating solution regulating tank 608 is provided with a temperature controller 610, and a plating solution analyzing unit 612 for sampling the plating solution and analyzing the sample solution. Further, component replenishing pipes 614 for replenishing the plating solution with components which are found to be insufficient by an analysis performed by the plating solution analyzing unit 612 are connected to the plating solution regulating tank 608. When a pump 616 is operated, the plating solution in the plating solution regulating tank 608 flows in the plating solution supply pipe 618, passes through the filter 620, and is then returned to the plating solution tray 600.

In this manner, the composition and temperature of the plating solution is adjusted to be constant in the plating solution regulating tank 608, and the adjusted plating solution is supplied to the electrode head 502 of the plating apparatus 818. Then, by holding the adjusted plating solution by the electrode head 502, the plating solution having constant composition and temperature at all times can be supplied to the electrode head 502 of the plating apparatus 818.

FIGS. 11 and 12 show an example of a cleaning and drying apparatus 820 for cleaning (rinsing) the substrate W and drying the substrate W. Specifically, the cleaning and drying apparatus 820 performs chemical cleaning and pure water cleaning (rinsing) first, and then completely drying the substrate W which has been cleaned by spindle rotation. The cleaning and drying apparatus 820 comprises a substrate holder 422 having a clamp mechanism 420 for clamping an edge portion of the substrate W, and a substrate mounting and removing lifting/lowering plate 424 for opening and closing the clamp mechanism 420.

The substrate holder 422 is coupled to an upper end of a spindle 426 which is rotated at a high speed by energization of a spindle rotating motor (not shown). Further, a cleaning cup 428 for preventing a treatment liquid from being scattered around is disposed around the substrate W held by the clamp mechanism 420, and the cleaning cup 428 is vertically moved by actuation of a cylinder (not shown).

Further, the cleaning and drying apparatus 820 comprises a chemical liquid nozzle 430 for supplying a treatment liquid to the surface of the substrate W held by the clamp mechanism 420, a plurality of pure water nozzles 432 for supplying pure water to the backside surface of the substrate W, and a pencil-type cleaning sponge 434 which is disposed above the substrate W held by the clamp mechanism 420 and is rotatable. The pencil-type cleaning sponge 434 is attached to a free end of a swing arm 436 which is swingable in a horizontal direction. Clean air introduction ports 438 for introducing clean air into the apparatus are provided at the upper part of the cleaning and drying apparatus 820.

With the cleaning and drying apparatus 820 having the above structure, the substrate W is held by the clamp mechanism 420 and is rotated by the clamp mechanism 420, and while the swing arm 436 is swung, a treatment liquid is supplied from the chemical liquid nozzle 430 to the cleaning sponge 434, and the surface of the substrate W is rubbed with the pencil-type cleaning sponge 434, thereby cleaning the surface of the substrate W. Further, pure water is supplied to the backside surface of the substrate W from the pure water nozzles 432, and the backside surface of the substrate W is simultaneously cleaned (rinsed) with the pure water ejected from the pure water nozzles 432. Thus cleaned substrate W is spin-dried by rotating the spindle 426 at a high speed.

FIG. 13 shows an example of a bevel etching and backside cleaning apparatus 822. The bevel etching and backside cleaning apparatus 822 can perform etching of the copper layer 7 (see FIG. 6B) deposited on an edge (bevel) of the substrate and backside cleaning simultaneously, and can suppress growth of a natural oxide film of copper at the circuit formation portion on the surface of the substrate. The bevel etching and backside cleaning apparatus 822 has a substrate holder 922 positioned inside a bottomed cylindrical waterproof cover 920 and adapted to rotate the substrate W at a high speed, in such a state that the face of the substrate W faces upward, while holding the substrate W horizontally by spin chucks 921 at a plurality of locations along a circumferential direction of a peripheral edge portion of the substrate, a center nozzle 924 placed above a nearly central portion of the face of the substrate W held by the substrate holder 922, and an edge nozzle 926 placed above the peripheral edge portion of the substrate W. The center nozzle 924 and the edge nozzle 926 are directed downward. Aback nozzle 928 is positioned below a nearly central portion of the backside of the substrate W, and directed upward. The edge nozzle 926 is adapted to be movable in a diametrical direction and a height direction of the substrate W.

The width of movement L of the edge nozzle 926 is set such that the edge nozzle 926 can be arbitrarily positioned in a direction toward the center from the outer peripheral end surface of the substrate, and a set value for L is inputted, according to the size, usage, or the like of the substrate W. Normally, an edge cut width C is set in the range of 2 mm to 5 mm. In the case where a rotational speed of the substrate is a certain value or higher at which the amount of liquid migration from the backside to the face is not problematic, the copper layer, and the like within the edge cut width C can be removed.

Next, the method of cleaning with this bevel etching and backside cleaning apparatus 822 will be described. First, the substrate W is horizontally rotated together with the substrate holder 922, with the substrate being held horizontally by the spin chucks 921 of the substrate holder 922. In this state, an acid solution is supplied from the center nozzle 924 to the central portion of the face of the substrate W. The acid solution may be a non-oxidizing acid, and hydrofluoric acid, hydrochloric acid, sulfuric acid, citric acid, oxalic acid, or the like is used. On the other hand, an oxidizing agent solution is supplied continuously or intermittently from the edge nozzle 926 to the peripheral edge portion of the substrate W. As the oxidizing agent solution, one of an aqueous solution of ozone, an aqueous solution of hydrogen peroxide, an aqueous solution of nitric acid, and an aqueous solution of sodium hypochlorite is used, or a combination of these is used.

In this manner, the copper layer, or the like formed on the upper surface and end surface in the region of the edge cut width C of the substrate W is rapidly oxidized with the oxidizing agent solution, and is simultaneously etched with the acid solution supplied from the center nozzle 924 and spread on the entire face of the substrate, whereby it is dissolved and removed. By mixing the acid solution and the oxidizing agent solution at the peripheral edge portion of the substrate, a steep etching profile can be obtained, in comparison with a mixture of them which is produced in advance being supplied. At this time, the copper etching rate is determined by their concentrations. If a natural oxide film of copper is formed in the circuit-formed portion on the face of the substrate, this natural oxide is immediately removed by the acid solution spreading on the entire face of the substrate according to rotation of the substrate, and does not grow anymore. After the supply of the acid solution from the center nozzle 924 is stopped, the supply of the oxidizing agent solution from the edge nozzle 926 is stopped. As a result, silicon exposed on the surface is oxidized, and deposition of copper can be suppressed.

On the other hand, an oxidizing agent solution and a silicon oxide film etching agent are supplied simultaneously or alternately from the back nozzle 928 to the central portion of the backside of the substrate. Therefore, copper or the like adhering in a metal form to the backside of the substrate W can be oxidized with the oxidizing agent solution, together with silicon of the substrate, and can be etched and removed with the silicon oxide film etching agent. This oxidizing agent solution is preferably the same as the oxidizing agent solution supplied to the face, because the types of chemicals are decreased in number. Hydrofluoric acid can be used as the silicon oxide film etching agent, and if hydrofluoric acid is used as the acid solution on the face of the substrate, the types of chemicals can be decreased in number. Thus, if the supply of the oxidizing agent is stopped first, a hydrophobic surface is obtained. If the etching agent solution is stopped first, a water-saturated surface (a hydrophilic surface) is obtained, and thus the backside surface can be adjusted to a condition that will satisfy the requirements of a subsequent process.

In this manner, the acid solution, i.e., etching solution is supplied to the substrate W to remove metal ions remaining on the surface of the substrate W. Then, pure water is supplied to replace the etching solution with pure water and remove the etching solution, and then the substrate is dried by spin-drying. In this way, removal of the copper layer in the edge cut width C at the peripheral edge portion on the face of the substrate, and removal of copper contaminants on the backside are performed simultaneously to thus allow this treatment to be completed, for example, within 80 seconds. The etching cut width of the edge can be set arbitrarily (from 2 to 5 mm), but the time required for etching does not depend on the cut width.

FIGS. 14 and 15 show a heat treatment (annealing) apparatus 826. The annealing apparatus 826 comprises a chamber 1002 having a gate 1000 for taking in and taking out the substrate W, a hot plate 1004 disposed at an upper position in the chamber 1002 for heating the substrate W to e.g. 400° C., and a cool plate 1006 disposed at a lower position in the chamber 1002 for cooling the substrate W by, for example, flowing cooling water inside the plate 1006. The annealing apparatus 26 also has a plurality of vertically movable elevating pins 1008 penetrating the cool plate 1006 and extending upward and downward there through for placing and holding the substrate W on them. The annealing apparatus further includes a gas introduction pipe 1010 for introducing an antioxidant gas between the substrate W and the hot plate 1004 during annealing, and a gas discharge pipe 1012 for discharging the gas which has been introduced from the gas introduction pipe 1010 and flowed between the substrate W and the hot plate 1004. The pipes 1010 and 1012 are disposed on the opposite sides of the hot plate 1004.

The gas introduction pipe 1010 is connected to a mixed gas introduction line 1022 which in turn is connected to a mixer 1020 where a N₂ gas introduced through a N₂ gas introduction line 1016 containing a filter 1014 a, and a H₂ gas introduced through a H₂ gas introduction line 1018 containing a filter 1014 b, are mixed to form a mixed gas which flows through the line 1022 into the gas introduction pipe 1010.

In operation, the substrate W, which has been carried in the chamber 1002 through the gate 1000, is held on the elevating pins 1008 and the elevating pins 1008 are raised up to a position at which the distance between the substrate W held on the lifting pins 1008 and the hot plate 1004 becomes about 0.1 to 1.0 mm, for example. In this state, the substrate W is then heated to e.g. 400° C. through the hot plate 1004 and, at the same time, the antioxidant gas is introduced from the gas introduction pipe 1010 and the gas is allowed to flow between the substrate W and the hot plate 1004 while the gas is discharged from the gas discharge pipe 1012, thereby annealing the substrate W while preventing its oxidation. The annealing treatment may be completed in about several tens of seconds to 60 seconds. The heating temperature of the substrate may be selected in the range of 100 to 600° C.

After the completion of the annealing, the elevating pins 1008 are lowered down to a position at which the distance between the substrate W held on the elevating pins 1008 and the cool plate 1006 becomes 0 to 0.5 mm, for example. In this state, by introducing cooling water into the cool plate 1006, the substrate W is cooled by the cool plate 1006 to a temperature of 100° C. or lower in about 10 to 60 seconds. The cooled substrate is transferred to the next step.

In this embodiment, a mixed gas of N₂ gas with several percentages of H₂ gas is used as the above antioxidant gas. However, N₂ gas may be used singly.

FIGS. 16 through 22 show a pretreatment apparatus 828 for performing a pretreatment of electroless plating of the substrate. The pretreatment apparatus 828 includes a fixed frame 152 that is mounted on the upper part of a frame 150, and a movable frame 154 that moves up and down relative to the fixed frame 152. A processing head 160, which includes a bottomed cylindrical housing portion 156, opening downwardly, and a substrate holder 158, is suspended from and supported by the movable frame 154. In particular, a servomotor 162 for rotating the head is mounted to the movable frame 154, and the housing portion 156 of the processing head 160 is coupled to the lower end of the downward-extending output shaft (hollow shaft) 164 of the servomotor 162.

As shown in FIG. 19, a vertical shaft 168, which rotates together with the output shaft 164 via a spline 166, is inserted in the output shaft 164, and the substrate holder 158 of the processing head 160 is coupled to the lower end of the vertical shaft 168 via a ball joint 170. The substrate holder 158 is positioned within the housing portion 156. The upper end of the vertical shaft 168 is coupled via a bearing 172 and a bracket to a fixed ring-elevating cylinder 174 secured to the movable frame 154. Thus, by the actuation of the cylinder 174, the vertical shaft 168 moves vertically independently of the output shaft 164.

Linear guides 176, which extend vertically and guide vertical movement of the movable frame 154, are mounted to the fixed frame 152, so that by the actuation of a head-elevating cylinder (not shown), the movable frame 154 moves vertically by the guide of the linear guides 176.

Substrate insertion windows 156 a for inserting the substrate W into the housing portion 156 are formed in the circumferential wall of the housing portion 156 of the processing head 160. Further, as shown in FIGS. 20 and 21, a seal ring 184 is provided in the lower portion of the housing portion 156 of the processing head 160, an outer peripheral portion of the seal ring 184 a being sandwiched between a main frame 180 made of e.g. PEEK and a guide frame 182 made of e.g. polyethylene. The seal ring 184 a is provided to make contact with a peripheral portion of the lower surface of the substrate W to seal the peripheral portion of the substrate W.

On the other hand, a substrate fixing ring 186 is fixed to a peripheral portion of the lower surface of the substrate holder 158. Columnar pushers 190 each protrudes downwardly from the lower surface of the substrate fixing ring 186 by the elastic force of a spring 188 disposed within the substrate fixing ring 186 of the substrate holder 158. Further, a flexible cylindrical bellows-like plate 192 made of e.g. Teflon (registered trademark) is disposed between the upper surface of the substrate holder 158 and the upper wall of the housing portion 156 to hermetically seal therein.

When the substrate holder 158 is in a raised position, a substrate W is inserted from the substrate insertion window 156 a into the housing portion 156. The substrate W is then guided by a tapered surface 182 a provided in the inner circumferential surface of the guide frame 182, and positioned and placed at a predetermined position on the upper surface of the seal ring 184 a. In this state, the substrate holder 158 is lowered so as to bring the pushers 190 of the substrate fixing ring 186 into contact with the upper surface of the substrate W. The substrate holder 158 is further lowered so as to press the substrate W downwardly by the elastic forces of the springs 188, thereby forcing the seal ring 184 a to make pressure contact with a peripheral portion of the front surface (lower surface) of the substrate W to seal the peripheral portion while nipping the substrate W between the housing portion 56 and the substrate holder 58 to hold the substrate W.

When the head-rotating servomotor 162 is driven while the substrate W is thus held by the substrate holder 158, the output shaft 164 and the vertical shaft 168 inserted in the output shaft 164 rotate together with via the spline 166, whereby the substrate holder 158 rotates together with the housing portion 156.

At a position below the processing head 160, there is provided an upward-open treatment tank 100 comprising an outer tank 100 a and an inner tank 100 b which have a slightly larger inner diameter than the outer diameter of the processing head 160. A pair of leg portions 104, which is mounted to a lid 102, is rotatably supported on the outer circumferential portion of the treatment tank 100. Further, a crank 106 is integrally coupled to each leg portion 106, and the free end of the crank 106 is rotatably coupled to the rod 110 of a lid-moving cylinder 108. Thus, by the actuation of the lid-moving cylinder 108, the lid 102 moves between a treatment position at which the lid 102 covers the top opening of the treatment tank 100 and a retreat position beside the treatment tank 100. In the surface (upper surface) of the lid 102, there is provided a nozzle plate 112 having a large number of jet nozzles 112 a for jetting outwardly (upwardly), electrolytic ionic water having reducing power, as described below, for example.

Further, as shown in FIG. 22, a nozzle plate 124 having a plurality of jet nozzles 124 a for jetting upwardly a chemical liquid supplied from a chemical liquid tank 120 by driving the chemical liquid pump 122 is provided in the inner tank 100 b of the treatment tank 100 in such a manner that the jet nozzles 124 a are equally distributed over the entire surface of the cross section of the inner tank 100 b. A drainpipe 126 for draining a chemical liquid (waste liquid) to the outside is connected to the bottom of the inner tank 100 b. A three-way valve 128 is provided in the drainpipe 126, and the chemical liquid (waste liquid) is returned to the chemical liquid tank 120 through a return pipe 130 connected to one of ports of the three-way valve 128 to recycle the chemical liquid, as needed. Further, in this embodiment, the nozzle plate 112 provided on the surface (upper surface) of the lid 102 is connected to a rinsing liquid supply source 132 for supplying a rinsing liquid such as pure water. Further, a drainpipe 127 is connected to the bottom of the outer tank 100 a.

By lowering the processing head 60 holding the substrate so as to cover or close the top opening of the treatment tank 100 with the processing head 60 and then jetting a chemical liquid from the jet nozzles 124 a of the nozzle plate 124 disposed in the inner tank 100 b of the treatment tank 100 toward the substrate W, the chemical liquid can be jetted uniformly onto the entire lower surface (surface to be processed) of the substrate W and the chemical liquid can be discharged out from the discharge pipe 126 while preventing scattering of the chemical liquid to the outside. Further, by raising the processing head 60 and closing the top opening of the treatment tank 100 with the lid 102, and then jetting a rinsing liquid from the jet nozzles 112 a of the nozzle plate 112 disposed in the upper surface of the lid 102 toward the substrate W held in the processing head 60, the rinsing treatment (cleaning treatment) is carried out to remove the chemical liquid from the surface of the substrate. Because the rinsing liquid passes through the clearance between the outer tank 100 a and the inner tank 100 b and is discharged through the drainpipe 127, the rinsing liquid is prevented from flowing into the inner tank 100 b and from being mixed with the chemical liquid.

According to the pretreatment apparatus 828, the substrate W is inserted into the processing head 160 and held therein when the processing head 160 is in the raised position, as shown in FIG. 16. Thereafter, as shown in FIG. 17, the processing head 160 is lowered to the position at which it covers the top opening of the treatment tank 100. While rotating the processing head 160 and thereby rotating the substrate W held in the processing head 160, a chemical liquid is jetted from the jet nozzles 124 a of the nozzle plate 124 disposed in the treatment tank 100 toward the substrate W, thereby jetting the chemical liquid uniformly onto the entire surface of the substrate W. The processing head 160 is raised and stopped at a predetermined position and, as shown in FIG. 18, the lid 102 in the retreat position is moved to the position at which it covers the top opening of the treatment tank 100. A rinsing liquid is then jetted from the jet nozzles 112 a of the nozzle plate 112 disposed in the upper surface of the lid 102 toward the rotating substrate W held in the processing head 160. The chemical treatment by the chemical liquid and the rinsing treatment by the rinsing liquid of the substrate W can thus be carried out successively while avoiding mixing of the two liquids.

The lowermost position of the processing head 160 may be adjusted to adjust the distance between the substrate W held in the processing head 160 and the nozzle plate 124, whereby the region of the substrate W onto which the chemical liquid is jetted from the jet nozzles 124 a of the nozzle plate 124 and the jetting pressure can be adjusted as desired. Here, when the pretreatment liquid such as a chemical liquid is circulated and reused, active components are reduced by progress of the treatment, and the pretreatment liquid (chemical liquid) is taken out due to attachment of the pretreatment liquid to the substrate. Therefore, it is desirable to provide a pretreatment liquid management unit (not shown) for analyzing composition of the pretreatment liquid and adding insufficient components. Specifically, a chemical liquid used for cleaning is mainly composed of acid or alkali. Therefore, for example, a pH of the chemical liquid is measured, a decreased content is replenished from the difference between a preset value and the measured pH, and a decreased amount is replenished using a liquid level meter provided in the chemical liquid storage tank. Further, with respect to a catalytic liquid, for example, in the case of acid palladium solution, the amount of acid is measured by its pH, and the amount of palladium is measured by a titration method or nephelometry, and a decreased amount can be replenished in the same manner as the above.

FIGS. 23 through 29 show an electroless plating apparatus 830. This electroless plating apparatus 830, which is provided to form the protective film 9 shown in FIG. 6D, includes a plating tank 200 (see FIGS. 27 and 29), and a substrate head 204, disposed above the plating tank 200, for detachably holding a substrate W.

As shown in detail in FIG. 23, the processing head 204 has a housing 230 and a head portion 232. The head portion 232 mainly comprises a suction head 234 and a substrate receiver 236 for surrounding the suction head 234. The housing 230 accommodates therein a substrate rotating motor 238 and substrate receiver drive cylinders 240. The substrate rotating motor 238 has an output shaft (hollow shaft) 242 having an upper end coupled to a rotary joint 244 and a lower end coupled to the suction head 234 of the head portion 232. The substrate receiver drive cylinders 240 have respective rods coupled to the substrate receiver 236 of the head portion 232. Stoppers 246 are provided in the housing 230 for mechanically limiting upward movement of the substrate receiver 236.

The suction head 234 and the substrate receiver 236 are operatively connected to each other by a splined structure such that when the substrate receiver drive cylinders 240 are actuated, the substrate receiver 236 vertically moves relative to the suction head 234, and when the substrate rotating motor 238 is energized, the output shaft 242 thereof is rotated to rotate the suction head 234 and the substrate receiver 236 in unison with each other.

As shown in detail in FIGS. 24 through 26, a suction ring 250 for attracting and holding a substrate W against its lower surface to be sealed is mounted on a lower circumferential edge of the suction head 234 by a presser ring 251. The suction ring 250 has a recess 250 a continuously defined in a lower surface thereof in a circumferential direction and in communication with a vacuum line 252 extending through the suction head 234 by a communication hole 250 b that is defined in the suction ring 250. When the recess 250 a is evacuated, the substrate W is attracted to and held by the suction ring 250. Because the substrate W is attracted under vacuum to the suction ring 250 along a radially narrow circumferential area provided by the recess 250 a, any adverse effects such as flexing caused by the vacuum on the substrate W are minimized. When the suction ring 250 is dipped in the plating solution (treatment liquid), not only the surface (lower surface) of the substrate W, but also its circumferential edge, can be dipped in the plating solution. The substrate W is released from the suction ring 250 by introducing N₂ into the vacuum line 252.

The substrate receiver 236 is in the form of a downwardly open, hollow bottomed cylinder having substrate insertion windows 236 a defined in a circumferential wall thereof for inserting therethrough the substrate W into the substrate receiver 236. The substrate receiver 236 also has an annular ledge 254 projecting inwardly from its lower end, and an annular protrusion 256 disposed on an upper surface of the annular ledge 254 and having a tapered inner circumferential surface 256 a for guiding the substrate W.

As shown in FIG. 24, when the substrate receiver 236 is lowered, the substrate W is inserted through the substrate insertion window 236 a into the substrate receiver 236. The substrate W thus inserted is guided by the tapered surface 256 a of the protrusion 256 and positioned thereby onto the upper surface of the ledge 254 in a predetermined position thereon. The substrate receiver 236 is then elevated until it brings the upper surface of the substrate W placed on the ledge 254 into abutment against the suction ring 250 of the suction head 234, as shown in FIG. 25. Then, the recess 250 a in the vacuum ring 250 is evacuated through the vacuum line 252 to attract the substrate W while sealing the upper peripheral edge surface of the substrate W against the lower surface of the suction ring 250. In order to plate the substrate W, as shown in FIG. 26, the substrate receiver 236 is lowered several mm to space the substrate W from the ledge 254, keeping the substrate W attracted only by the suction ring 250. The substrate W now has its lower peripheral edge surface prevented from not being plated because it is held out of contact with the ledge 254.

FIG. 27 shows the details of the plating tank 200. The plating tank 200 is connected at the bottom to a plating solution supply pipe 308 (see FIG. 29), and is provided in the peripheral wall with a plating solution recovery groove 260. In the plating tank 200, there are disposed two current plates 262, 264 for stabilizing the flow of a plating solution flowing upward. A thermometer 266 for measuring the temperature of the plating solution introduced into the plating tank 200 is disposed at the bottom of the plating tank 200. Further, on the outer surface of the peripheral wall of the plating tank 200 and at a position slightly higher than the liquid level of the plating solution held in the plating tank 200, there is provided a jet nozzle 268 for jetting a stop liquid which is a neutral liquid having a pH of 6 to 7.5, for example, pure water, inwardly and slightly upwardly in the normal direction. After plating, the substrate W held in the head portion 232 is raised and stopped at a position slightly above the surface of the plating solution. In this state, pure water (stop liquid) is immediately jetted from the jet nozzle 268 toward the substrate W to cool the substrate W, thereby preventing progress of plating by the plating solution remaining on the substrate W.

Further, at the top opening of the plating tank 200, there is provided an openable/closable plating tank cover 270 which closes the top opening of the plating tank 200 in a non-plating time, such as idling time, so as to prevent unnecessary evaporation of the plating solution from the plating tank 200.

As shown in FIG. 29, a plating solution supply pipe 308 extending from a plating solution storage tank 302 and having a plating solution supply pump 304 and a three-way valve 306 is connected to the plating tank 200 at the bottom of the plating tank 200. With this arrangement, during a plating process, a plating solution is supplied into the plating tank 200 from the bottom of the plating tank 200, and the overflowing plating solution is recovered by the plating solution storage tank 302 through the plating solution recovery groove 260. Thus, the plating solution can be circulated. A plating solution return pipe 312 for returning the plating solution to the plating solution storage tank 302 is connected to one of the ports of the three-way valve 306. Thus, the plating solution can be circulated even in a standby condition of plating, and a plating solution circulating system is constructed. As described above, the plating solution in the plating solution storage tank 302 is always circulated through the plating solution circulating system, and hence a lowering rate of the concentration of the plating solution can be reduced and the number of the substrates W which can be processed can be increased, compared with the case in which the plating solution is simply stored.

Particularly, in this embodiment, by controlling the plating solution supply pump 304, the flow rate of the plating solution which is circulated at a standby of plating or at a plating process can be set individually. Specifically, the amount of circulating plating solution at the standby of plating is in the range of 2 to 20 litter/minute, for example, and the amount of circulating plating solution at the plating process is in the range of 0 to 10 litter/minute, for example. With this arrangement, a large amount of circulating plating solution at the standby of plating can be ensured to keep a temperature of the plating bath in the cell constant, and the flow rate of the circulating plating solution is made smaller at the plating process to form a protective film (plated film) having a more uniform thickness.

The thermometer 266 provided in the vicinity of the bottom of the plating tank 200 measures a temperature of the plating solution introduced into the plating tank 200, and controls a heater 316 and a flow meter 318 described below.

Specifically, in this embodiment, there are provided a heating device 322 for heating the plating solution indirectly by a heat exchanger 320 which is provided in the plating solution in the plating solution storage tank 302 and uses water as a heating medium which has been heated by a separate heater 316 and has passed through the flow meter 318, and a stirring pump 324 for mixing the plating solution by circulating the plating solution in the plating solution storage tank 302. This is because in the plating, in some cases, the plating solution is used at a high temperature (about 80° C.), and the structure should cope with such cases. This method can prevent very delicate plating solution from being mixed with foreign matter or the like unlike an in-line heating method.

FIG. 28 shows the details of a cleaning tank 202 provided beside the plating tank 200. At the bottom of the cleaning tank 202, there is provided a nozzle plate 282 having a plurality of jet nozzles 280, attached thereto, for upwardly jetting a rinsing liquid such as pure water. The nozzle plate 282 is coupled to an upper end of a nozzle lifting shaft 284. The nozzle lifting shaft 284 can be moved vertically by changing the position of engagement between a nozzle position adjustment screw 287 and a nut 288 engaging the screw 287 so as to optimize the distance between the jet nozzles 280 and a substrate W located above the jet nozzles 280.

Further, on the outer surface of the peripheral wall of the cleaning tank 202 and at a position above the jet nozzles 280, there is provided a head cleaning nozzle 286 for jetting a cleaning liquid, such as pure water, inwardly and slightly downwardly onto at least a portion, which was in contact with the plating solution, of the head portion 232 of the substrate head 204.

In operating the cleaning tank 202, the substrate W held in the head portion 232 of the substrate head 204 is located at a predetermined position in the cleaning tank 202. A cleaning liquid (rinsing liquid), such as pure water, is jetted from the jet nozzles 280 to clean (rinse) the substrate W, and at the same time, a cleaning liquid, such as pure water, is jetted from the head cleaning nozzle 286 to clean at least a portion, which was in contact with the plating solution, of the head portion 232 of the substrate head 204, thereby preventing a deposit from accumulating on that portion which was immersed in the plating solution.

According to this electroless plating apparatus 830, when the substrate head 204 is in a raised position, the substrate W is held by vacuum attraction in the head portion 232 of the substrate head 204 as described above, while the plating solution in the plating tank 200 is allowed to circulate.

When plating is performed, the plating tank cover 270 of the plating tank 200 is opened, and the substrate head 204 is lowered, while the substrate head 204 is rotating, so that the substrate W held in the head portion 232 is immersed in the plating solution in the plating tank 200.

After immersing the substrate W in the plating solution for a predetermined time, the substrate head 204 is raised to lift the substrate W from the plating solution in the plating tank 200 and, as needed, pure water (stop liquid) is immediately jetted from the jet nozzle 268 toward the substrate W to cool the substrate W, as described above. The substrate head 204 is further raised to lift the substrate W to a position above the plating tank 200, and the rotation of the substrate head 204 is stopped.

Next, while the substrate W is held by vacuum attraction in the head portion 232 of the substrate head 204, the substrate head 204 is moved to a position right above the cleaning tank 202. While rotating the substrate head 204, the substrate head 204 is lowered to a predetermined position in the cleaning tank 202. A cleaning liquid (rinsing liquid), such as pure water, is jetted from the jet nozzles 280 to clean (rinse) the substrate W, and at the same time, a cleaning liquid, such as pure water, is jetted from the head cleaning nozzle 286 to clean at least a portion, which was in contact with the plating solution, of the head portion 232 of the substrate head 204.

After completion of cleaning of the substrate W, the rotation of the substrate head 204 is stopped, and the substrate head 204 is raised to lift the substrate W to a position above the cleaning tank 202. Further, the substrate head 204 is moved to the transfer position between the transfer robot 816 and the substrate head 204, and the substrate W is transferred to the transfer robot 816, and is transported to a next process by the transfer robot 816.

As shown in FIG. 29, the electroless plating apparatus 830 is provided with a plating solution management unit 330 for measuring an amount of plating liquid held by the electroless plating apparatus 830 and for analyzing composition of the plating solution by an absorptiometric method, a titration method, an electrochemical measurement, or the like, and replenishing components which are insufficient in the plating solution. In the plating solution management unit 330, signals indicative of the analysis results are processed to replenish insufficient components from a replenishment tank (not shown) to the plating solution storage tank 302 using a metering pump, thereby controlling the amount of the plating solution and composition of the plating solution. Thus, thin film plating can be realized in a good reproducibility.

The plating solution management unit 330 has a dissolved oxygen densitometer 332 for measuring dissolved oxygen in the plating solution held by the electroless plating apparatus 830 by an electrochemical method, for example. According to the plating solution management unit 330, dissolved oxygen concentration in the plating solution can be controlled at a constant value on the basis of indication of the dissolved oxygen densitometer 332 by deaeration, nitrogen blowing, or other methods. In this manner, the dissolved oxygen concentration in the plating solution can be controlled at a constant value, and the plating reaction can be achieved in a good reproducibility.

When the plating solution is used repeatedly, certain components are accumulated by being carried in from the outside or decomposition of the plating solution, resulting in lowering of reproducibility of plating and deteriorating of film quality. By adding a mechanism for removing such specific components selectively, the life of the plating solution can be prolonged and the reproducibility can be improved.

FIG. 30 shows an example of a polishing apparatus (CMP apparatus) 832. The polishing apparatus 832 comprises a polishing table 842 having a polishing surface composed of a polishing cloth (polishing pad) 840 which is attached to the upper surface of the polishing table 842, and a top ring 844 for holding a substrate W with its to-be-polished surface facing the polishing table 842. In the polishing apparatus 832, the surface of the substrate W is polished by rotating the polishing table 842 and the top ring 844 about their own axes, respectively, and supplying a polishing liquid from a polishing liquid nozzle 846 provided above the polishing table 842 while pressing the substrate W against the polishing cloth 840 of the polishing table 842 at a given pressure by means of the top ring 844. It is possible to use a fixed abrasive type of pad containing fixed abrasive particles as the polishing pad.

The polishing power of the polishing surface of the polishing cloth 840 decreases with a continuation of a polishing operation of the CMP apparatus 832. In order to restore the polishing power, a dresser 848 is provided to conduct dressing of the polishing cloth 840, for example, at the time of replacing the substrate W. In the dressing, while rotating the dresser 848 and the polishing table 842 respectively, the dressing surface (dressing member) of the dresser 848 is pressed against the polishing cloth 840 of the polishing table 842, thereby removing the polishing liquid and chips adhering to the polishing surface and, at the same time, flattening and dressing the polishing surface, whereby the polishing surface is regenerated. The polishing table 842 may be provided with a monitor for monitoring the surface state of the substrate to detect in situ an end point of polishing, or with a monitor for inspecting in situ the finish state of the substrate.

FIGS. 31 and 32 show the film thickness measuring instrument 824 provided with a reversing machine. As shown in the FIGS. 31 and 32, the film thickness measuring instrument 824 is provided with a reversing machine 339. The reversing machine 339 includes reversing arms 353, 353. The reversing arms 353, 353 put a substrate W therebetween and hold its outer periphery from right and left sides, and rotate the substrate W through 180°, thereby turning the substrate over. A circular mounting base 355 is disposed immediately below the reversing arms 353, 353 (reversing stage), and a plurality of film thickness sensors S are provided on the mounting base 355. The mounting base 355 is adapted to be movable upward and downward by a drive mechanism 357.

During reversing of the substrate W, the mounting base 355 waits at a position, indicated by solid lines, below the substrate W. Before or after reversing, the mounting base 355 is raised to a position indicated by dotted lines to bring the film thickness sensors S close to the substrate W gripped by the reversing arms 353, 353, thereby measuring a film thickness.

According to this embodiment, since there is no restriction such as the arms of the transfer robot, the film thickness sensors S can be installed at arbitrary positions on the mounting base 355. Further, the mounting base 355 is adapted to be movable upward and downward, so that the distance between the substrate W and the sensors S can be adjusted at the time of measurement. It is also possible to mount plural types of sensors suitable for the purpose of detection, and change the distance between the substrate W and the sensors each time measurements are made by the respective sensors. However, the mounting base 355 moves upward and downward, thus requiring certain measuring time.

An eddy current sensor, for example, may be used as the film thickness sensor S. The eddy current sensor measures a film thickness by generating an eddy current and detecting the frequency or loss of the current that has returned through the substrate W, and is used in a non-contact manner. An optical sensor may also be suitable for the film thickness sensor S. The optical sensor irradiates a light onto a sample, and measures a film thickness directly based on information of the reflected light. The optical sensor can measure a film thickness not only for a metal film but also for an insulating film such as an oxide film. Places for setting the film thickness sensor S are not limited to those shown in the drawings, but the sensor may be set at any desired places for measurement in any desired numbers.

Next, a sequence of processing for forming copper interconnects on the substrate having the seed layer 6 shown in FIG. 6A, which is carried out by the substrate processing apparatus having the above structure, will be described with reference to FIG. 33.

First, the substrate W having the seed layer 6 formed in its surface is taken out one by one from a transfer box 810, and is carried in the loading/unloading station 814. The substrate W, which has carried in the loading/unloading station 814, is transferred to the thickness measuring instrument 824 by the transfer robot 816, and an initial film thickness (film thickness of the seed layer 6) is measured by the thickness measuring instrument 824. Thereafter, if necessary, the substrate is inverted and transferred to the plating apparatus 818. In the plating apparatus 818, as shown in FIG. 6B, the copper layer 7 is deposited on the surface of the substrate W to embed copper.

Then, the substrate W having the copper layer 7 formed thereon is transferred to the cleaning and drying apparatus 820 by the transfer robot 816, and the substrate W is cleaned by pure water and spin-dried. Alternatively, in a case where a spin-drying function is provided in the plating apparatus 818, the substrate W is spin-dried (removal of liquid) in the plating apparatus 818, and then the dried substrate is transferred to the bevel etching and backside cleaning apparatus 822.

In the bevel etching and backside cleaning apparatus 822, unnecessary copper attached to the bevel (edge) of the substrate W is removed by etching, and at the same time, the backside surface of the substrate is cleaned by pure water or the like. Thereafter, as described above, the substrate W is transferred to the cleaning and drying apparatus 820 by the transfer robot 816, and the substrate W is cleaned by pure water and spin-dried. Alternatively, in a case where a spin-drying function is provided in the bevel etching and backside cleaning apparatus 822, the substrate W is spin-dried in the bevel etching and backside cleaning apparatus 822, and then the dried substrate is transferred to the heat treatment apparatus 826 by the transfer robot 816.

In the heat treatment apparatus 826, heat treatment (annealing) of the substrate W is carried out. Then, the substrate W after the heat treatment is transferred to the film thickness measuring instrument 824 by the transfer robot 816, and the film thickness of copper is measured by the film thickness measuring instrument 824. The film thickness of the copper layer 7 (see FIG. 6B) is obtained from the difference between this measured result and the measured result of the above initial film thickness. Then, for example, plating time of a subsequent substrate is adjusted according to the measured film thickness. If the film thickness of the copper layer 7 is insufficient, then additional formation of copper layer is performed by plating again. Then, the substrate W after the film thickness measurement is transferred to the polishing apparatus 832 by the transfer robot 816.

As shown in FIG. 6C, unnecessary copper layer 7, the seed layer 6 and the barrier layer 5 deposited on the surface of the substrate W are polished and removed by the polishing apparatus 832 to flatten the surface of the substrate W. At this time, for example, the film thickness or the finishing state of the substrate is inspected by a monitor, and when an end point is detected by the monitor, polishing is finished. Then, the substrate W which has been polished is transferred to the cleaning and drying apparatus 820 by the transfer robot 816, and the surface of the substrate is cleaned by a chemical liquid and then cleaned (rinsed) with pure water, and then spin-dried by rotating the substrate at a high speed in the cleaning and drying apparatus 820. After this spin-drying, the substrate W is transferred to the pretreatment apparatus 828 by the transfer robot 816.

In the pretreatment apparatus 828, a pretreatment before plating comprising at least one of attachment of Pd catalyst to the surface of the substrate and removal of oxide film attached to the exposed surface of the substrate, for example, is carried out. Then, the substrate after this pretreatment, as described above, is transferred to the cleaning and drying apparatus 820 by the transfer robot 816, and the substrate W is cleaned by pure water and spin-dried. Alternatively, in a case where a spin-drying function is provided in the pretreatment apparatus 828, the substrate W is spin-dried (removal of liquid) in the pretreatment apparatus 828, and then the dried substrate is transferred to the electroless plating apparatus 830 by the transfer robot 816.

In the electroless plating apparatus 830, as shown in FIG. 6D, for example, electroless Co—W—P plating is applied to the surfaces of the exposed interconnects 8 to form a protective film (plated film) 9 composed of Co—W—P alloy selectively on the exposed surfaces of the interconnects 8, thereby protecting the interconnects 8. The thickness of the protective film 9 is in the range of 0.1 to 500 nm, preferably in the range of 1 to 200 nm, more preferably in the range of 10 to 100 nm. At this time, for example, the thickness of the protective film 9 is monitored, and when the film thickness reaches a predetermined value, i.e., an end point is detected, the electroless plating is finished.

After the electroless plating, the substrate W is transferred to the cleaning and drying apparatus 820 by the transfer robot 816, and the surface of the substrate is cleaned by a chemical liquid, and cleaned (rinsed) with pure water, and then spin-dried by rotating the substrate at a high speed. After the spin-drying, the substrate W is returned into the transfer box 810 via the loading/unloading station 814 by the transfer robot 816.

In this embodiment, copper is used as an interconnect material. However, besides copper, a copper alloy, silver, a silver alloy, and the like may be used.

As described in detail hereinabove, according to the present invention, the use of an anode made of an insoluble material can avoid the need for a change of anode and, in addition, obviate the generation of particles due to the peeling of a black film which would occur when using a soluble anode. Further, oxygen gas generated at the surface of the insoluble anode during plating can be introduced into the anode changer, and the oxygen gas in the anode chamber can then be discharged so that the oxygen gas will not reach the substrate. This can prevent the oxygen gas from causing defects in the substrate.

FIG. 34 shows a plating apparatus according another embodiment of the present invention. The plating apparatus 700 includes a plating cell 710 for storing a plating solution Q, an anode 720 provided in the plating cell 710, a plating solution impregnated material 730 disposed above the anode 720, a filter 740 provided between the plating solution impregnated material 730 and the anode 720, a plurality of plating solution supply pipes 751, 753, 755 for supplying the plating solution Q into the plating cell 710 and circulating the plating solution Q, a contact member 760 provided on the upper surface of the plating solution impregnated material 730, a substrate holder 770 for holding a substrate W with its front surface (surface to be plated) facing downwardly, and a holder drive mechanism 790 for vertically moving and rotating or scroll-rotating the substrate holder 770. The plating solution supply pipes 751, 753, 755 all together constitute a plating solution supply section.

The plating cell 710 is formed in the shape of an upwardly-open container, and an overflow tank 711 is provided around the upper portion of the outer circumferential surface of the plating cell 710. The lower chamber, partitioned by the filter 740, in the plating cell 710 constitutes an anode chamber 713 in which the anode 720 is disposed.

The anode 720 may be composed of the same metal as the metal to be plated, or an insoluble metal such as platinum, titanium, etc., or an insoluble electrode comprising a metal base plated with e.g. platinum. As with the preceding embodiment, because of no necessity for a change, etc., an insoluble metal or an insoluble electrode is preferred. The anode 720 is housed in an anode cup 721, and is to be connected to the anode of a plating power source 797. Though the anode 720 of this embodiment is tabular, it is also possible to house a plurality of ball-shaped anodes in the anode cup 721.

The plating solution impregnated material 730 may be composed of the same material as the plating solution impregnated material 532 (see e.g. FIG. 8) of the preceding embodiment and, when impregnated with the plating solution (electrolytic solution), constitutes a high-resistance structure having a lower electric conductivity than the electric conductivity of the plating solution. Since the plating solution impregnated 730, which serves as the high-resistance structure, is disposed on the plating cell 710 side, its diametrical size can be made larger than the diametrical size of the substrate W.

A membrane filter having numerous fine holes (holes with a diameter of e.g. about 0.1 μm), an ion-exchange resin membrane, a filter composed of PP or PE fibers compressed into the form of a sheet, etc. may be used as the filter 740. The filter 740 has a function of passing the plating solution Q therethrough, but blocking passage of particles, such as those coming from a so-called black film.

The plating solution supply section includes a plating solution supply pipe 751 that passes through the center of the bottom of the plating cell 710 and penetrates through the center of the anode 720, and is inserted centrally into the plating solution impregnated material 730, a plurality of plating solution supply pipes 753 for supplying the plating solution Q from the bottom of the plating cell 710 into the plating cell 710 on the side below the anode 720, and a plating solution supply pipe 755 for supplying the plating solution Q from above the contact member 760 provided in an upper position in the plating cell 710. Thus, the plating solution supply pipe 751 supplies the plating solution Q directly into the plating solution impregnated material 730, the plating solution supply pipes 753 supply the plating solution Q into the anode chamber 713 of the plating cell 710, and the plating solution supply pipe 755 supplies the plating solution Q directly onto the upper surface of the contact member 760. The plating solution Q, supplied into the plating cell 710 via the plating solution supply pipes 751, 753, 755, is discharged out of the plating cell 710 via a plurality of discharge pipes 757, provided in the sidewall of the plating cell 710, and the overflow tank 711 and is circulated.

With respect to the contact member 760, as with the lower pad 534 a (see e.g. FIG. 8) of the preceding embodiment, its surface (upper surface) to make contact with the surface (surface to be plated), having an electrical conductor layer (seed layer 6 shown in FIG. 6A), of the substrate W should have a high smoothness and have fine through-holes that permit passage therethrough of the plating solution Q. Further, in order to avoid plating deposition on the contact member 760 itself, at least the contact surface should be made of an insulator or a material having high insulating properties. Furthermore, in order to firmly hold a flat surface of the substrate W and suppress plating deposition on the contact portion to a minimum, the contact surface should have a certain level of hardness. The smoothness required for the contact member 760 is not more than several tens of μm in terms of the maximum roughness (RMS). The fine through-holes required for the contact member 760 are preferably round through-holes in order to keep flatness of the contact surface with the substrate W. Though the optimum hole size (diameter), the number of holes per unit area, etc. of the fine through-holes vary depending upon the quality of a plated film and the interconnect pattern, the selectivity of the growth of a plated film in recesses and raised portions is enhanced with a smaller hole size and a smaller number of holes. The thickness of the contact member 760 is preferably 0.01 to 20 mm, more preferably 0.1 to 5 mm.

The material of the contact member 760 that meets the above requirements may be the same as the above-described lower pad 534 a.

The substrate holder 770 holds the substrate W with its front surface (surface to be plated) facing downwardly. According to this embodiment, the substrate holder 770 attracts and holds the substrate W by vacuum-attracting or electrostatically attracting the back surface of the substrate W. In a peripheral portion of the lower surface of the substrate holder 770 is provided a cathode 771 for feeding electricity from the peripheral bevel portion of the substrate W to the electrical conductor layer of the surface to be plated of the substrate W. The cathode 771 is to be connected to the cathode of the plating power source 796.

The holder drive mechanism 790 includes a rotational drive shaft 791 connected to the center of the upper surface of the substrate holder 70, a scroll drive shaft 793 for causing the rotational drive shaft 791 to make a scroll movement, and a drive section 795 for rotationally driving the shafts 791, 793 and driving the substrate holder 770 to move vertically. With the provision of the holder drive mechanism 790, it is possible to rotate or scroll-rotate the substrate W, held by the substrate holder 770, by the drive section 795, and lower the substrate holder 770 so as to bring the surface to be plated of the substrate W into contact with the plating solution Q over the upper surface of the contact member 760 or bring the surface to be plated into pressure contact with the upper surface of the contact member 760.

The plating power source 796 is to apply a plating voltage between the anode 720 and the electrical conductor layer of the surface to be plated of the substrate W, as described above, and generally applies a positive potential to the anode 720 and a negative potential to the substrate W. Depending upon the manner of using the plating apparatus 700, the plating power source 796 may be designed to be able to switch between positive potential application and negative potential application.

A method for metal-plating the surface to be plated of the substrate W by the plating apparatus 700 having the above-described construction will now be described.

First, the plating solution Q is supplied from the plating solution supply pipes 753 into the plating cell 710, the plating solution Q is supplied from the plating solution supply pipe 751 into the plating solution impregnated material 730 and the contact member 760, and the plating solution Q is also supplied from the plating solution supply pipe 755 onto the upper surface of the contact member 760. At the same time, the plating solution Q is discharged out of the plating cell 710 via the discharge pipes 757 and the overflow tank 711. The discharged plating solution Q, after removing impurities from it by, for example, passing it through a filter, is returned into the plating cell 710 via the plating solution supply pipes 751, 753, 755. In this manner, the plating solution Q is circulated.

Since the interior of the plating cell 710 is partitioned by the plating solution impregnated material 730, the plating solution Q supplied from the plating solution supply pipes 753 mainly fills the anode chamber 713, the plating solution Q supplied from the plating solution supply pipe 751 mainly fills the interior of the plating solution impregnated material 730 and the interior of the contact member 760, and the plating solution Q supplied from the plating solution supply pipe 755 mainly fills the space above the contact member 760. The plating solution Q in each of the above regions can pass through the filter 740, the plating solution impregnated material 730 and the contact member 760 into the other region. However, the amount of such transferring plating solution is small. Accordingly, it is easily possible to vary the compositions of the respective plating solutions Q to be supplied from the plating solution supply pipes 751, 753, 755 so as to meet the intended uses of the respective regions.

In particular, with respect to the plating solution Q to be supplied from the plating solution supply pipe 755, a plating solution may be used which contains a suitable additive for embedding a plating metal into the interconnect trenches and fine holes of the substrate W. With respect to the plating solution Q to be supplied from the plating solution supply pipes 551, 553, a plating solution not containing the above additive or a plating solution having a different composition from that of the above plating solution may be used. Instead of the supply of the plating solution Q onto the upper surface of the contact member 760 via the plating solution supply pipe 755, it is also possible to omit the plating solution supply pipe 755 and supply the plating solution Q from the plating solution supply pipes 751, 753 through the plating solution impregnated material 730 and the contact member 760 onto the upper surface of the contact member 760.

Next, while circulating the plating solution Q in the above-described manner, the substrate holder 770, holding the substrate W face down on the lower surface of the holder 770, is lowered by the holder drive mechanism 790 to bring the surface to be plated of the substrate W into contact with the plating solution Q. A voltage is applied from the plating power source 796 to between the anode 720 and the electrical conductor layer of the substrate W to pass electric current therebetween, thereby effecting plating (e.g. copper plating) onto the electrical conductor layer of the substrate surface. During the plating, the surface to be plated of the substrate W is allowed to be in contact with the contact member 760 in the below-described manner.

According to this embodiment, plating is carried out while keeping the surface to be plated of the substrate W in contact with the contact member 760. While the surface to be plated of the substrate W is kept in contact with the contact member 760, it is possible to rotationally drive the substrate holder 770 so as to slide the surface to be plated of the substrate W on the surface of the contact member 760. It is also possible to repeat the contact and non-contact between the contact member 760 and the surface to be plated of the substrate W at appropriate time intervals during plating.

By thus carrying out plating while keeping the surface to be plated of the substrate W in contact with the contact member 760, it becomes possible to supply the plating solution Q preferentially into the interconnect trenches and fine holes of the substrate W, thereby depositing the metal preferentially onto the surfaces of the interconnect trenches and the fine holes.

FIG. 35 schematically shows the contact surface and its vicinity when the contact member 760 is in contact with the surface to be plated of the substrate W. Though not shown in FIG. 35, the electrical conductor layer (seed layer 6) has been formed by a common method on the surface to be plated of the substrate W, as shown in FIG. 6A. The contact member 760 having a high surface flatness is in contact with the surface of the electrical conductor layer. Since the contact member 760 is formed of an insulator or a material having high insulating properties, only the portions of the numerous fine through-holes 761 of the contact member 760 are electrically conductive. Thus, the plating solution in the fine recesses (fine holes 3 and interconnect trenches 4 shown in FIG. 6A) W1 of the substrate W communicates with the plating solution under the contact member 760 only through the fine through-holes 761, and an electric current flows only through the fine through-holes 761 to effect plating.

When application of current is started in the state shown in FIG. 35, plating is effected selectively only in the fine recesses W1 filled with the plating solution. Though metal ions in the fine recesses W1 are consumed with the process of plating, a fresh plating solution is supplied through the fine through-holes 761 of the contact member 760 into the fine recesses W1, whereby plating proceeds. After filling in the fine recesses W1 with the plated film, the application of current is stopped and the substrate holder 770 is raised by the holder drive mechanism 790 to separate the contact member 760 and the substrate W. The substrate W is then subjected to the next process step, such as cleaning.

If the contact and non-contact between the contact member 760 and the substrate W are repeated during plating, a fresh plating solution Q favorably can enter the fine recesses W1 more easily when the contact member 760 and the substrate W are apart.

In some cases, it is possible to carry out ordinary plating in the plating solution Q while keeping the substrate W apart from the contact member 760 before, after or during plating carried out by allowing the substrate W to be in contact with the contact member 760. For example, after carrying out plating for a short time while keeping the surface to be plated of the substrate W apart from the contact member 760, the surface to be plated is brought into contact with the contact member 760 to carry out the above-described plating.

According to this embodiment, because of the presence of the plating solution impregnated material 730 as a high-resistance structure between the substrate W and the anode 720, uniform plating over the entire surface to be plated of the substrate W can be effected whether plating is carried out while keeping the substrate W in contact with the contact member 760 or while keeping the substrate W apart from the contact member 760. In particular, electricity is fed to the peripheral bevel portion of the substrate W. Without the plating solution impregnated material 730, since the electric resistance of the electrical conductor layer increases with the distance from the periphery of the substrate W, potential variation is produced in the surface of the substrate W, resulting in variation of the plating rate. The presence of the plating solution impregnated material 730, which has such a large resistance as to make the electric resistance difference in the surface of the substrate W negligible, can equalize the plating rate. Further according to this embodiment, the substrate W is held face down, and the plating solution impregnated material 730 is provided on the plating cell 710 side. Accordingly, the diametrical size of the plating solution impregnated material 730 can be made larger than the diametrical size of the substrate W with ease, whereby more uniform plating can be effected.

Further, by rotating or scroll-rotating the substrate W in this embodiment, even more uniform plating becomes possible over the entire surface to be plated of the substrate W. The rotation or scroll movement of the substrate W may be performed either when plating is carried out while keeping the substrate W in contact with the contact member 760 or when plating is carried out while keeping the substrate W apart from the contact member 760.

During plating, a so-called black film produced at the anode 720 floats in the plating solution Q in the anode chamber 713. However, the plating solution impregnated material 730 and, according to this embodiment, also the contact member 760 and the filter 740 can prevent the movement of the black film to the substrate W side.

As described above, since the anode chamber 713 is defined by the filter 740 (or by the plating solution impregnated material 730 in case of not providing the filter 740) in the plating apparatus 700, it is possible to easily control the composition (amount of ions, amounts of additives and composition of additives) of the plating solution Q in the anode chamber 713 and the composition of the plating solution Q above the contact member 760 for use in plating of the substrate W respectively at the optima (the two compositions may be identical).

As another method to promote the growth of plated film in the fine recesses W1, it is possible to employ a method which involves a repetition of the contact and non-contact between the contact member 760 and the substrate W, and an intermittent power supply in accordance with the contact/non-contact, in particular a method which comprises supplying a power only when the substrate W is in contact with the contact member 760 (or a method which comprises supplying a higher power when the substrate W is in contact with the contact member 760).

FIG. 36 schematically shows a current change A in the fine recesses W1 of the substrate W and a current change B in the other surface portion of the substrate W as observed in plating carried out at a constant voltage. The graph in FIG. 36 is made only in consideration of the balance between supply and consumption of copper ions, while the adsorption, decomposition, consumption, etc. of an additive is not taken into account.

In electroplating, when there is a plenty of fresh plating solution over a portion to be plated, the plating solution contains metal ions in a large amount and thus has a low electric resistance. Accordingly, a high electric current flows in the plating solution. However, if the supply of plating solution is insufficient, the resistance of the plating solution increases with the consumption of the metal ions in the plating solution, whereby the electric current decreases. The amount of plating solution differs greatly between the space surrounded by the surface portion of the substrate W and the surface of the contact member 760 and the space surrounded by the fine recesses W1 and the surface of the contact member 760, and therefore there is a difference in the time at which the resistance of plating solution begins to increase. Thus, the current value begins to decrease at an earlier time (a₁) in the surface portion of the substrate W, while the current value begins to decrease at a considerably later time (a₂) in the fine recesses W1. The respective currents become constant after the times (b₁, b₂) at which the supply and consumption of the metal ions (copper ions) become balanced. The time at which the current becomes constant and the constant current value vary depending upon the width, the hole size, the number, etc. of the fine recesses W1. In the case of a constant current control, a rise in the voltage occurs in response to the above current decrease.

By applying a voltage or electric current in a pulsed manner (i.e. on/off or decrease/increase of voltage/current in a pulsed manner) in synchronization with the cycle of contact/non-contact between the contact member 760 and the substrate W, it becomes possible to further promote the growth of plated film in the fine recesses W1 compared to the surface portion of the substrate W. In this case, it is most effective to make the pulse width equal to the time period (a₂) until the current begins to decrease in the fine recesses W1. Further, since a fresh plating solution is supplied into the fine recesses W1 upon the contact/non-contact operation, there is no need to make the current density small for the purpose of ensuring the film quality, hence there is no significant lowering of the throughput. In order to improve the in-plane film thickness distribution of the plated film formed on the substrate W, it is possible to change the relative position between the contact member 760 and the substrate W by the holder drive mechanism 790 during the non-contact time, as described above.

As yet another method to promote the growth of plated film in the fine recesses W1, instead of the repetition of contact/non-contact between the contact member 760 and the substrate W (or in combination with the contact/non-contact between the contact member 760 and the substrate W), it is possible to employ a method which comprises changing the pressure of the substrate W on the contact member 760 upon contact from a relatively high pressure to a low pressure and, at the same time, changing the voltage application condition according to the change in pressure. The change of the voltage application condition includes an intermittent voltage application, an increase/decrease of applied voltage (repetition of high voltage and low voltage), etc. The voltage application may be application of a simple direct-current voltage, application of a pulse voltage as a group of pulses, or application of a sine-wave voltage. A method of carrying out plating by employing the change of the voltage application condition in association with a change of pressing condition of the substrate W on the contact member 760 may be carried out in the following two manners:

The first manner relates to the case where the change of the pressing condition is a change of the intensity of the pressure of the surface to be plated of the substrate W on the contact member 760 and the change of the voltage application condition is an intermittent voltage application. According to this manner, for example, a voltage is applied when the above pressure is relatively high to carry out plating, whereas a voltage is not applied when the pressure is relatively low to stop plating and a fresh plating solution is supplied between the fine recesses W1 of the substrate W and the contact member 760.

The second manner relates to the case where the change of the pressing condition is a change of the intensity of the pressure of the surface to be plated of the substrate W on the contact member 760 and the change of the voltage application condition is a change of the intensity of applied voltage. According to this manner, for example, a high voltage is applied when the above pressure is relatively high to carry out plating, whereas a low voltage is applied when the pressure is relatively low and a fresh plating solution is supplied to replace the plating solution in the fine recesses W1 which was consumed upon the high voltage application.

As a method for solving the above-described problem illustrated in FIG. 1 and improving the flatness of a plated film formed on the electrical conductor layer of the surface to be plated of the substrate W, it is possible to employ a method which comprises electrolytically plating the electrical conductor layer of the substrate W by any one of the above-described methods or by an ordinary plating method in which the substrate W is not contacted with the contact member 760, and electrolytically etching the electrical conductor layer of the substrate W while allowing the substrate W to be in contact with the contact member 760 and slide on the contact member 760. According to this method, electrolytic etching can be performed while polishing the surface of the substrate W with the contact member 760. Thus, it becomes possible to rub off a thin film at the topmost layer of a raised portion of the plated film formed over a narrow trench, and selectively etch away the exposed plated layer, thereby improving the flatness of the plated film. In this case, at least the surface of the contact member 760 that is to make contact with the substrate W should preferably be made of a flexible and durable material. The following is a specific manner of carrying out this method.

When carrying out electroplating by the plating apparatus 700 shown in FIG. 34, as described above, the operation of bringing the surface to be plated of the substrate W into contact with the contact member 760 and the operation of detaching the surface to be plated from the contact member 760 are repeated, or the pressure of the substrate W on the contact member 760 is changed during plating. Alternatively, plating is carried out by a common method, that is, by applying current while keeping the surface to be plated of the substrate W apart from the contact member 760 at a given distance with the plating solution interposed therebetween.

When carrying out electrolytic etching, on the other hand, the positive and the negative of the plating power source 796 are reversed so as to make the electrical conductor layer of the substrate W an anode and change the anode 720 to a cathode. Thereafter, the holder drive mechanism 790 is driven to lower the substrate holder 770 so as to press the surface to be plated of the substrate W on the contact member 760 at a predetermined pressure while the substrate holder 770 is rotated, thereby etching the surface to be plated of the substrate W while rubbing the surface to be plated with the surface of the contact member 760. By thus performing electrolytic etching during plating and carrying out the electrolytic etching while pressing the surface to be plated of the substrate W on the surface of the contact member 760 and moving the both surfaces relative to each other, it becomes possible to selectively etch away raised portions of the plated film formed over narrow trenches on the surface to be plated of the substrate W, thereby improving the flatness of the plated film. Thus, the above-described problem illustrated in FIG. 1 can be solved.

FIG. 37 is a schematic overall plan view of a plating processing facility 300 incorporating the plating apparatus 700 shown in FIG. 34. As shown in FIG. 37, the plating processing facility 300 includes three loading/unloading sections 301 for housing substrates W, four plating apparatuses 700, two transfer robots 303, 305 for transferring a substrate W between the loading/unloading sections 301 and the plating apparatuses 700, a bevel and back surface cleaning unit 307, a spin-drying unit 309, and a temporary substrate storage stage 311.

The transfer robot 303 takes a substrate W before plating out of a substrate cassette set in one of the loading/unloading sections 301 and places the substrate W on the temporary substrate storage stage 311. The other transfer robot 305 takes the substrate W on the temporary substrate storage stage 311 and transfers it to one of the plating apparatuses 700, where plating of the substrate W is carried out in the above-described manner. After completion of the plating, the substrate W is taken by the transfer robot 305 out of the plating apparatus 700 and transferred to the bevel and back surface cleaning unit 307, where the substrate W is cleaned. The substrate W is then transferred by the transfer robot 303 to the spin-drying unit 309, where the substrate W is dried. Thereafter, the substrate W is transferred by the transfer robot 303 to a substrate cassette set in one of the loading/unloading sections 301 and is housed in the cassette, whereby a series of plating processes of the substrate W is completed.

As described in detail hereinabove, the present invention makes it possible to plate a substrate uniformly over the entire surface to be plated of the substrate. Further, a metal plated film, such as a copper plated film, can be deposited selectively in interconnect trenches and fine holes formed in a substrate surface.

FIG. 38 is a schematic view of an electroplating apparatus provided with a substrate processing apparatus according to an embodiment of the present invention, showing the state of the plating apparatus during plating, FIG. 39 is a schematic view of the main portion of the substrate holding apparatus (substrate processing apparatus), showing the state of the apparatus before holding of a substrate, and FIG. 40 is a schematic view of the main portion of the substrate holding apparatus, showing the state of the apparatus after holding of the substrate. Though in this embodiment the substrate processing apparatus of the present invention is employed as a substrate holding apparatus in an electroplating apparatus, the present substrate processing apparatus can also be employed as a substrate holding apparatus in other electrolytic processing apparatus, such as an electrolytic etching apparatus, or in a polishing apparatus. Further, though in this embodiment a substrate is held with its front surface (surface to be processed) facing upwardly (face up) in processing of the substrate, it is, of course, possible to hold and process a substrate with its front surface facing downward (face down). In the following description, the same or equivalent members as or to the members shown in FIGS. 2 through 4 are given the same reference numerals, and a duplicate description thereof is omitted.

As shown in FIG. 38, the electroplating apparatus is mainly comprised of a substrate holding apparatus (substrate processing apparatus) 40 and an electrode head 42. The substrate holding apparatus 40 includes a generally disk-shaped substrate holder 12 coupled to the upper end of a vertically-movable spline shaft 10. A vacuum passage 12 a, having a number of suction ports opening at the upper surface of the substrate holder 12, is provided within the substrate holder 12. The vacuum passage 12 a communicates with a vacuum passage 10 a that vertically penetrates the spline shaft 10, and the vacuum passage 10 a is connected to a vacuum line 46 extending from a vacuum source 44, such as a vacuum pump. A substrate W, supported on the upper surface of the substrate holder 12, is attracted and held on the substrate holder 12 through vacuuming of the vacuum passage 12 a, provided within the substrate holder 12, by the vacuum source 44. The holding by attraction of the substrate W is released by breaking the vacuum.

The use of the substrate holder 12, which holds a substrate W by vacuum attraction, can avoid the need to provide an outwardly-projecting holding member, such as a mechanical chuck, and can securely hold the substrate which is supported by a positioning guide, as will be described later.

A fluid flow passage 12 b as a temperature control section for allowing a heat medium to flow in it so as to control the temperature of the substrate holder 12 at a constant temperature is provided within the substrate holder 12. The fluid flow passage 12 b communicates at one end with one fluid flow passage 10 b that vertically penetrates the spline shaft 10 and at the other end with the other fluid flow passage 10 c that vertically penetrates the spline shaft 10. The fluid flow passage 10 b is connected to a heat medium supply line 50 extending from a heat medium supply source 48, and the fluid flow passage 10 c is connected to a heat medium discharge line 52 extending from the heat medium supply source 48. A heat medium, which may be a heating medium or a cooling medium, whose temperature is controlled by the heat medium supply source 48, is thus supplied into the fluid flow passage 12 b within the substrate holder 12 and flows in one direction along the fluid flow passage 12 b in a circulative manner, thereby controlling the temperature of the substrate holder 12 and also the temperature of the substrate W held by the substrate holder 12 at a constant temperature.

By thus controlling not only the temperature of a chemical liquid, such as a plating solution, but also the temperature of the substrate holder 12 and a substrate W held by the substrate holder 12 at a constant temperature, the effect of a chemical liquid, which is supplied to the substrate W upon processing of the substrate, can be maximized. Though in this embodiment the temperature control section is comprised of the fluid flow passage 12 b, the temperature control section may also be comprised of, for example, an electric heater, a Peltier device or a thermocouple.

On the upper surface of a rotating disk 16 coupled to the upper end of a main shaft 14, a positioning guide 54, which is generally cylindrical and has a downwardly-tapering tapered surface 54 a, is provided concentrically with the substrate holder 12 such that it surrounds the circumference of the substrate holder 12. The diameter D₁ of the upper end opening of the tapered surface 54 a of the positioning guide 54 is set to be larger than the sum of the diameter of a substrate W to be held by the substrate holder 12 and the maximum error for the substrate W. In particular, in the case of a φ300 mm substrate, the diameter D₁ is larger than the sum of 300 m and the maximum error +0.2 mm, i.e. 300.2 mm. Thus, with a necessary margin added to the sum, the diameter D₁ is set at e.g. about 302 to 310 mm. The diameter D₂ of the lower end opening of the tapered surface 54 a is set to be smaller than the sum of the diameter of the substrate W to be held by the substrate holder 12 and the minimum error for the substrate W. In particular, in the case of a φ300 mm substrate, the diameter D₂ is smaller than the sum of 300 mm and the minimum error −0.2 mm, i.e. 299.8 mm. Thus, with a necessary margin added to the sum, the diameter D₂ is set at e.g. about 290 to 299 mm. The inclination angle θ of the tapered surface 54 a is set at e.g. 5 to 30°.

As the substrate holder 12 descends, as described below, the substrate W supported on the substrate holder 12 enters smoothly into the inside of the positioning guide 54 without interfering with the positioning guide 54. As the substrate holder 12 further descends, the substrate W comes to be supported by the positioning guide 54, without falling off the positioning guide 54, and only the substrate holder 12 continues to descent.

The positioning guide 54, in consideration of chemical resistance, low friction, strength, processibility, etc., is formed of a PEEK material. Other resin materials, such as PTFE, PCTFE, PVC, PP, etc., may also be employed. A metal material, such as a stainless steel or titanium, is of course usable as a material for the positioning guide 54. The positioning guide 54 is subjected to water cleaning, cleaning with a chemical and spin-drying after the completion of plating, and therefore is desirably of a well-drained shape. Further, it is desirable that water cleaning or chemical cleaning of the substrate W and the positioning guide 54 be carried out while they are positioned such that the distance between them is smallest.

The positioning guide 54 rotates together with the substrate holder 12 by the rotation of the main shaft 14. The positioning guide 54 is not provided with a movable member for positioning, and positioning of the substrate W with respect to the substrate holder 12 is completed merely by placing the substrate W on the surface of the positioning guide 54.

Support posts 32 are mounted on the peripheral portion of the rotating disk 16, and at the top of the support posts 32 are provided, as shown in FIG. 38, inwardly-projecting cathodes 34 which, when the substrate W is in a raised position (plating position), make contact with a peripheral portion of the substrate W to feed electricity to the substrate, and an inwardly-projecting ring-shaped seal ring 36 which makes pressure contact with a peripheral portion of the substrate W in the plating position to seal the peripheral portion. The seal ring 36 is composed of a composite material comprising a core 56 of metal covered with a covering material 58 of rubber having elasticity. A material having good corrosion resistance, such as a stainless steel, titanium or Hasteloy, is preferred as the core (metal) 56. A fluorocarbon rubber, a silicone rubber or a resin elastomer is preferred as the covering material (rubber). It is, of course, possible to use other metals and rubbers depending upon the chemical used, etc.

The seal ring 36 composed of such a composite material comprising a metal covered with a rubber has an enhanced rigidity and improved shape stability. When the substrate W is sealed with the seal ring 36, as shown in FIGS. 41A and 41B, the deformation of the seal ring 36 can be small enough to securely prevent a leak of plating solution. Further, because of the high dimensional accuracy of the seal ring 36, the distance S of the sealing boundary from the peripheral end surface of the substrate W can be made substantially equal constantly.

When attracting and holding the substrate W by the substrate holding apparatus 40, the substrate W is first placed on the upper surface of the substrate holder 12, which is in a somewhat raised position, so that the substrate W is supported horizontally on the upper surface. The substrate W is in a condition to be movable horizontally along the upper surface of the substrate holder 12. While keeping the substrate W in a horizontal position, the substrate holder 12 is lowered to bring the peripheral end surface of the substrate W into contact with the tapered surface 54 a of the positioning guide 54 over substantially the entire circumference of the peripheral end surface, as shown in FIG. 39. The substrate holder 12 is further lowered so as to shift the support of the substrate W by the substrate holder 12 to support of the substrate W by the tapered surface 54 a of the positioning guide 54, thereby positioning the substrate W with respect to the substrate holder 12.

According to necessity, the substrate holder 12 is again raised so as to horizontally support and raise the substrate W which has been supported by the tapered surface 54 a of the positioning guide 54, and the substrate holder 12 is then lowered so as to shift the support of the substrate W by the substrate holder 12 to the support of the substrate W by the tapered surface 54 a of the positioning guide 54. This operation may be repeated one or more times.

Next, while keeping the substrate holder 12 in a condition to attract and hold the substrate W, i.e. while vacuuming the vacuum passage 12 a provided within the substrate holder 12 via the vacuum source 44, the substrate holder 12 is raised and when the upper surface of the substrate holder 12 contacts the substrate W supported by the tapered surface 54 a of the positioning guide 54, the substrate W is attracted and held on the upper surface of the substrate holder 12, as shown in FIG. 40. The substrate holder 12 is further raised and stopped.

According to this embodiment, positioning of the substrate W with respect to the substrate holder 12 is thus performed by bringing the peripheral end surface of the substrate W as a reference into contact with the tapered surface 54 a of the positioning guide 54. In this positioning, the center position of the substrate W does not change regardless of the diameter of the substrate W, i.e., regardless of any dimensional error in the diameter. Thus, positioning of the substrate W with respect to the substrate holder 12 can be performed with accuracy without being influenced by the diametrical size of the substrate W. In particular, when there is a dimensional error in the diametrical size of the substrate W, though the height position of the substrate W with respect to the positioning guide 54 changes (substrate W with a larger diameter is supported in an upper position by the tapered surface 54 a) upon contact of the substrate W in a horizontal position with the tapered surface 54 a of the positioning guide 54 to hold the substrate W, the center position of the substrate W with respect to the guide 54 does not change. Accordingly, when the substrate W is attracted and held by the substrate holder 12, for example, by means of a vacuum chuck, the center of the substrate W can coincide with the center of the substrate holder 12.

Further according to this embodiment, the positioning guide 54 has a cylindrical shape, and the tapered surface 54 a contacts the peripheral end surface of the substrate W over substantially the entire circumference of the peripheral end surface to position the substrate W with respect to the substrate holder 12. This enables a more accurate positioning of the substrate W with respect to the substrate holder 12. The cylindrical positioning guide 54 may have a cut-off portion e.g. for handling.

The electrode head 42 includes a housing 62 mounted to a vertically-movable support plate 60, and a high-resistance structure 64 disposed such that it closes the bottom opening of the housing 62. The housing 62 has at its bottom an inwardly-projecting portion 62 a and the high-resistance structure 64 has at its top a flange portion 64 a. The high-resistance structure 64 is held by the housing 62 with the flange portion 64 a caught on the inwardly-projecting portion 62 a. A hollow plating solution chamber 66 is thus defined inside the housing 62.

The high-resistance structure 64 of this embodiment is composed of the same material as the plating solution impregnated materials 532 (see e.g. FIG. 9) and 730 (see e.g. FIG. 34), and is designed to exhibit a lower electric conductivity than the electric conductivity of a plating solution by allowing the plating solution to flow into it and run along complicated, considerably long paths in the thickness direction.

The provision of the high-resistance structure 64, which exhibits a high electric resistance, makes it possible to make the influence of the resistance of e.g. the seed layer 6 (see FIG. 6A) formed on the surface of the substrate W negligibly small and make an in-plane difference in current density due to the electric resistance at the surface of the substrate W smaller, thereby enhancing the in-plane uniformity of plated film.

An anode 68 is disposed in the plating solution chamber 66, and a plating solution introduction pipe (not shown) for introducing a plating solution 70 into the plating solution chamber 66 is mounted to the housing 62. The plating solution 70, introduced from the plating solution supply pipe into the plating solution chamber 66, immerses the anode 68, passes through the high-resistance structure 64 and reaches to below the high-resistance structure 64.

In the case of performing copper plating, for example, in order to suppress the formation of slime, the anode 68 may be composed of copper (phosphor-containing copper) containing 0.03 to 0.05% of phosphor. The anode 68 may also be composed of an insoluble metal such as platinum, titanium, etc., or an insoluble electrode comprising a metal base plated with e.g. platinum. Because of no necessity for a change, an anode composed of an insoluble metal or an insoluble electrode is preferred. Further, because of permeability to plating solution, the anode 68 may have a net form.

The cathode 34 and the anode 68 are to be electrically connected to the cathode and the anode of a plating power source, respectively.

The operation of the plating apparatus in carrying out plating will now be described.

First, after performing accurate positioning of a substrate W in the above-described manner, the substrate W is attracted and held by the substrate holder 12. The substrate W is raised to a raised portion (plating position) as shown in FIG. 38 so as to bring the cathodes 34 into contact with a peripheral portion of the substrate W and, at the same, bring the seal ring 36 into pressure contact with a peripheral portion of the substrate W to seal that portion. Thereafter, the electrode head 42 is lowered, and the lowering of the electrode head 42 is stopped when the lower surface of the high-resistance structure 64 of the electrode head 42 has reached a position as close as about 0.1 to 3 mm to the surface of the substrate W. On the other hand, the plating solution 70 has been introduced into the plating solution chamber 66, and the high-resistance structure 64 has been impregnated with the plating solution.

In this state, the gap between the substrate W and the high-resistance structure 64 is filled with the plating solution 70 in an amount of e.g. not more than about 10 cc, and the cathodes 34 and the anode 68 are electrically connected to the cathode and the anode of the plating power source, respectively, thereby performing plating of the surface of the substrate W. During plating, the main shaft 14 is rotated, according to necessity, to rotate the substrate holder 12 at a rotational speed of e.g. 1-40 min⁻, thereby reducing localized plating on the substrate which would be caused by electric field concentration due to the shape of the electrode and enhancing the in-plane uniformity of the film thickness of the plated film formed. Further, according to necessity, a heat medium (heating medium or cooling medium) is allowed to flow in the fluid flow passage 12 b during plating so as to control (by heating or cooling) the temperature of the substrate holder 12 and the substrate W held by the substrate holder 12 at a constant temperature, as described above, thereby enhancing the plating performance. After completion of the plating, the electrode head 42 is raised and is moved to a retreat position.

Next, the plating solution 70 remaining on the substrate W is recovered, for example, by means of an aspirator nozzle, which is movable over the substrate W, until the amount of the residual liquid becomes e.g. about several cc. After the recovery of plating solution, the aspirator nozzle is returned to a retreat position.

Thereafter, while rotating the substrate holder 12 by rotating the main shaft 14, pure water is supplied to the surface of the substrate W to clean the surface of the substrate W with pure water. During the cleaning, the several cc of plating solution remaining on the surface of the substrate W is cleaned off with pure water, falling off the periphery of the seal ring 36 by centrifugal force. In order to minimize scattering of the diluted plating solution, the rotational speed of the substrate holder 12 is preferably controlled at several tens to a hundred and several tens min⁻¹.

Next, the substrate holder 12 is lowered to a position (cleaning position) as shown in FIG. 40 to thereby separate the substrate W from the seal ring 36 and the cathodes 34. Thereafter, while rotating the substrate holder 12 by rotating the main shaft 14, pure water is supplied to the surface of the substrate W to clean the surface of the substrate W with pure water and, at the same, clean the positioning guide 54. The rotational speed of the substrate holder 12 is preferably high enough to perform effective cleaning.

After the completion of water cleaning, the supply of pure water is stopped, and the rotational speed of the substrate holder 12 is increased to spin-dry the substrate W and the positioning guide 54.

After the spin-drying of the substrate W, the rotation of the substrate holder 12 is stopped, and the substrate holder 12 is lowered to a position (substrate transfer position) as shown in FIG. 39. Upon the lowering, the vacuum in the vacuum passage 12 a provided within the substrate holder 12 is broken. Thus, the substrate W, upon contact with the tapered surface 54 a of the positioning guide 54, detaches from the substrate holder 12 and, as described above, is supported by the tapered surface 54 a of the positioning guide 54 with accurate positioning.

Next, the substrate holder 12 is raised to support horizontally and raise the substrate W which has been supported by the tapered surface 54 a of the positioning guide 54, and the substrate W is sent to the next process step.

In this embodiment, the substrate processing apparatus according to the present invention is employed as a substrate holding apparatus in the electroplating apparatus. The substrate processing apparatus, when thus used as a substrate holding apparatus in an electroplating apparatus, can make the contact positions of a substrate, held by the substrate holder, with a cathode and a seal ring more accurate and can enhance the in-plane uniformity of the thickness of plated film regardless of an error in the diameter of the substrate. Further, margins that have conventionally been allowed for cathode contact position and seal ring contact position can be made smaller, for example, from 2.5 mm to 2.0 mm, thus making it possible to enlarge the effective area of a substrate.

The substrate processing apparatus can be employed as a substrate holding apparatus in an electrolytic etching apparatus by reversing the above-described anode and cathode, and using an etching liquid instead of a plating solution. It is, of course, possible to use the substrate processing apparatus as a substrate holding apparatus in a polishing apparatus.

According to the substrate processing apparatus of the present invention, the accuracy of positioning of a substrate with respect to a substrate holder can be enhanced without being influenced by a dimensional error in the diameter of the substrate. Thus, the substrate processing apparatus, when used as a substrate holding apparatus in an electroplating apparatus, can make the contact positions of a substrate, held by the substrate holder, with a cathode and a seal ring more accurate and can therefore enhance the in-plane uniformity of the thickness of plated film regardless of an error in the diameter of the substrate. Further, margins that have conventionally been allowed for cathode contact position and seal ring contact position can be made smaller, for example, from 2.5 mm to 2.0 mm, thus making it possible to enlarge the effective area of a substrate. This will contribute much to increasing the product yield now and in future years when the diametrical sizes of substrates are becoming increasingly large. 

1. A plating apparatus comprising: a substrate holder for holding a substrate; a cathode section including a seal ring for contacting a peripheral portion of a surface, to be plated, of the substrate held by the substrate holder to seal the peripheral portion water-tightly, and a cathode for contacting the substrate to supply current to the substrate; a vertically-movable electrode head provided above the cathode section, including an anode chamber housing an anode made of an insoluble material and having a bottom opening closed with a water-permeable porous member; a plating solution injection section for injecting a plating solution between the anode and the surface, to be plated, of the substrate held by the substrate holder; a power source for applying a plating voltage between the cathode and the anode; and a gas discharge line for discharging gas from the anode chamber.
 2. The plating apparatus according to claim 1, further comprising: a control section for controlling an amount of the gas discharged through the gas discharge line.
 3. The plating apparatus according to claim 2, further comprising: a pressure sensor for detecting the pressure in the anode chamber; wherein the control section controls the amount of the gas discharged through the gas discharge line based on an output of the pressure sensor.
 4. The plating apparatus according to claim 2, further comprising: an integrator for integrating an electric current flowing between the cathode and the anode; wherein the control section controls the amount of the gas discharged through the gas discharge line based on an output of the integrator.
 5. A plating method comprising: providing in a plating cell an anode and a plating solution impregnated material disposed above the anode, and filling the plating cell with a plating solution so that the plating solution impregnated material is immersed in the plating solution; bringing a downwardly-facing surface, to be plated, of a substrate into contact with the plating solution on the plating solution impregnated material; and applying a voltage between the anode and the surface, to be plated, of the substrate, thereby carrying out plating of the surface, to be plated.
 6. The plating method according to claim 5, wherein a contact member is provided on the upper surface of the plating solution impregnated material, and plating is carried out while keeping the surface, to be plated, of the substrate in contact with the upper surface of the contact member.
 7. The plating method according to claim 6, wherein the operation of applying a voltage between the surface, to be plated, of the substrate and the anode while keeping the surface, to be plated, of the substrate in contact with the upper surface of the contact member, and the operation of detaching the surface, to be plated, of the substrate from the upper surface of the contact member are repeated.
 8. The plating method according to claim 5, wherein the substrate is allowed to rotate or make a scroll movement while the surface, to be plated, of the substrate is kept in contact with the plating solution.
 9. The plating method according to claim 5, wherein the plating solution is supplied into the plating cell from below the plating solution impregnated material, and the plating solution is passed through the plating solution impregnated material and supplied to above the plating solution impregnated material.
 10. The plating method according to claim 5, wherein the plating solution is supplied from above the plating solution impregnated material onto the upper surface of the plating solution impregnated material.
 11. A plating apparatus comprising: an anode disposed in a plating cell; a plating solution impregnated material disposed above the anode; a plating solution supply section for supplying and filling a plating solution into the plating cell until the plating solution reaches to above the plating solution impregnated material; and a substrate holder for holding a substrate with its surface, to be plated, facing downwardly; wherein the surface, to be plated, of the substrate held by the substrate holder is brought into contact with the plating solution above the plating solution impregnated material to carry out plating of the surface, to be plated.
 12. The plating apparatus according to claim 11, further comprising: a contact member having a flat upper surface as a contact surface, provided above the plating solution impregnated material; and a holder drive mechanism for repeating the operation of bringing the surface, to be plated, of the substrate held by the substrate holder into contact with the contact surface of the contact member and the operation of detaching the surface, to be plated, from the contact surface of the contact member.
 13. The plating apparatus according to claim 12, wherein the holder drive mechanism includes a mechanism for vertically moving the substrate holder, and a mechanism for allowing the substrate holder to rotate or make a scroll movement.
 14. The plating apparatus according to claim 11, wherein the plating solution supply section includes a plating solution supply pipe for supplying the plating solution into the plating cell from below the anode, and a plating solution supply pipe for supplying the plating solution to above the plating solution impregnated material.
 15. The plating apparatus according to claim 11, wherein a filter is provided between the anode and the plating solution impregnated material.
 16. A substrate processing apparatus comprising: a vertically-movable substrate holder for supporting a substrate in a horizontal position and detachably holding the substrate; and a positioning guide disposed such that it surrounds the circumference of the substrate holder; wherein the positioning guide has a tapered surface which, when the substrate supported horizontally by the substrate holder is lowered or raised, contacts the peripheral end surface of the substrate to position the substrate with respect to the substrate holder.
 17. The substrate processing apparatus according to claim 16, wherein the positioning guide is formed in a cylindrical shape, and the tapered surface contacts the peripheral end surface of the substrate over substantially the entire circumference of the peripheral end surface to position the substrate with respect to the substrate holder.
 18. The substrate processing apparatus according to claim 16, wherein an electrode for contacting a peripheral portion of the substrate held by the substrate holder to supply current to the substrate, and a seal ring for pressure-contacting a peripheral portion of the substrate to seal the peripheral portion are provided above the substrate holder.
 19. The substrate processing apparatus according to claim 18, wherein the seal ring is composed of a composite material comprising a metal covered with a rubber.
 20. The substrate processing apparatus according to claim 16, wherein the substrate holder is designed to hold the substrate by vacuum attraction.
 21. The substrate processing apparatus according to claim 16, wherein a temperature control section for controlling the temperature of the substrate holder is provided within the substrate holder.
 22. The substrate processing apparatus according to claim 21, wherein the temperature control section comprises a fluid flow passage for allowing a temperature-controlled heat medium to flow therein.
 23. A substrate processing method comprising: lowering or raising a substrate supported horizontally by a substrate holder and bringing a peripheral end surface of the substrate into contact with a tapered surface of a positioning guide, disposed such that it surrounds the substrate holder, to position the substrate with respect to the substrate holder; and holding the substrate by the substrate holder.
 24. The substrate processing method according to claim 23, wherein the tapered surface of the positioning guide is brought into contact with the peripheral end surface of the substrate over substantially the entire circumference of the peripheral end surface to position the substrate with respect to the substrate holder.
 25. The substrate processing method according to claim 23, wherein the substrate held by the substrate holder is raised so as to bring an electrode into contact with a peripheral portion of the substrate to supply current to the substrate, and bring a seal ring into pressure contact with a peripheral portion of the substrate to seal the peripheral portion.
 26. The substrate processing method according to claim 25, wherein the seal ring is composed of a composite material comprising a metal covered with a rubber.
 27. The substrate processing method according to claim 23, wherein the substrate is held by the substrate holder by vacuum attraction.
 28. The substrate processing method according to claim 23, wherein the temperature of the substrate is controlled.
 29. The substrate processing method according to claim 28, wherein the temperature of the substrate holder is controlled by allowing a temperature-controlled heat medium to flow within the substrate holder. 